High-Index Borate Glasses

ABSTRACT

Glass compositions include boron oxide (B2O3), lanthanum oxide (La2O3), titania (TiO2) and niobia (Nb2O5) as essential components and may optionally include silica (SiO2), tungsten oxide (WO3), zirconia (ZrO2), yttria (Y2O3), bismuth oxide (Bi2O3), barium oxide (BaO), TeO2 and other components. The glasses may be characterized by high refractive index at 587.56 nm at comparably low liquidus temperature.

This application claims the benefit of priority to Dutch PatentApplication No. 2028260 filed on May 20, 2021, which claims priorityfrom U.S. Provisional Patent Application Ser. No. 63/163,269 filed onMar. 19, 2021, the content of which is relied upon and incorporatedherein by reference in its entirety.

FIELD

The present disclosure generally relates to borate and silicoborateglasses having a high refractive index and low density.

BACKGROUND

Glass is used in a variety of optical devices, examples of which includeaugmented reality devices, virtual reality devices, mixed realitydevices, eye wear, etc. Desirable properties for this type of glassoften include a high refractive index and a low density. Additionaldesirable properties may include high transmission in the visible andnear-ultraviolet (near-UV) range of the electromagnetic spectrum and/orlow optical dispersion. It can be challenging to find glasses having thedesired combination of these properties and which can be formed fromcompositions having good glass-forming ability. For example, generallyspeaking, as the refractive index of a glass increases, the density alsotends to increase. Species such as TiO₂ and Nb₂O₅ are often added toincrease the refractive index of a glass without increasing the densityof the glass. However, these materials often absorb blue and UV light,which can undesirably decrease the transmittance of light in this regionof the spectrum by the glass. Often, attempts to increase the refractiveindex of a glass while maintaining a low density, and without decreasingtransmittance in the blue and UV region of the spectrum, can result in adecrease in the glass-forming ability of the material. For example,crystallization and/or liquid-liquid phase separation can occur duringcooling of the glass melt at cooling rates that are generally acceptablein the industry. Typically, the decrease in glass-forming abilityappears as the amount of certain species, such as ZrO₂, Y₂O₃, Sc₂O₃,BeO, etc. increases.

Low density, high refractive index glasses often belong to one of twotypes of chemical systems, based on the glass formers used: (a)silicoborate or borosilicate glasses in which SiO₂ and/or B₂O₃ are usedas the main glass formers and (b) phosphate glasses in which P₂O₅ isused as a main glass former. Glasses which rely on other oxides as mainglass formers, such as GeO₂, TeO₂, Bi₂O₃, and V₂O₅, can be challengingto use due to cost, glass-forming ability, optical properties, and/orproduction requirements.

Phosphate glasses can be characterized by a high refractive index andlow density, however, phosphate glasses can be challenging to producedue to volatilization of P₂O₅ from the melts and/or risks of platinumincompatibility. In addition, phosphate glasses are often highly coloredand may require an extra bleaching step to provide a glass having thedesired transmittance characteristic.

Furthermore, phosphate glasses exhibiting a high refractive index alsotend to have an increase in optical dispersion.

Silicoborate and borate glasses are typically easier to produce and canexhibit a high transmittance without a bleaching step. However,silicoborate and borosilicate glasses typically exhibit an increase indensity at increasing refractive indices, compared to phosphate glasses.

In view of these considerations, there is a need for borate andsilicoborate glasses having a high refractive index, a low density, anda high transmittance to blue light.

SUMMARY

According to an embodiment of the present disclosure, a glass comprisesa plurality of components, the glass having a composition of thecomponents comprising greater than or equal to 3.0 mol. % and less thanor equal to 35.0 mol. % WO₃, greater than or equal to 0.3 mol. % andless than or equal to 50.0 mol. % TiO₂, greater than or equal to 0.3mol. % and less than or equal to 50.0 mol. % Nb₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 20.0 mol. % Bi₂O₃, greaterthan or equal to 0.0 mol. % and less than or equal to 10.0 mol. % TeO₂,greater than or equal to 0.0 mol. % and less than or equal to 5.0 mol. %PbO, greater than or equal to 0.0 mol. % and less than or equal to 3.0mol. % MoO₃, greater than or equal to 0.0 mol. % and less than or equalto 1.0 mol. % V₂O₅, greater than or equal to 0.0 at. % and less than orequal to 5.0 at. % F, greater than or equal to 0.0 at. % and less thanor equal to 1.0 at. % Cl, greater than or equal to 0.0 at. % and lessthan or equal to 1.0 at. % Br, greater than or equal to 0.0 at. % andless than or equal to 1.0 at. % I, greater than or equal to 0.6 mol. %and less than or equal to 60.0 mol. % TiO₂+Nb₂O₅ and may optionallycontain one or more components selected from Al₂O₃, B₂O₃, BaO, CaO,Gd₂O₃, GeO₂, K₂O, La₂O₃, Li₂O, MgO, Na₂O, P₂O₅, SiO₂, SrO, Ta₂O₅, Y₂O₃,Yb₂O₃, ZnO and ZrO₂, wherein the glass has a liquidus temperature,T_(liq) that is greater than or equal to 850° C. and less than or equalto 1350° C., and the glass satisfies the conditions: 1.92≤P_(n)≤2.08 andP_(n)−(1.437+0.0005*T_(liq))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

where a symbol “*” means multiplication.

According to another embodiment of the present disclosure, a glasscomprises a plurality of components, the glass having a composition ofthe components comprising greater than or equal to 7.5 mol. % and lessthan or equal to 28.0 mol. % TiO₂, greater than or equal to 1.0 mol. %and less than or equal to 40.0 mol. % B₂O₃, greater than or equal to 0.3mol. % and less than or equal to 19.5 mol. % Nb₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 35.0 mol. % WO₃, greaterthan or equal to 0.0 mol. % and less than or equal to 25.0 mol. % La₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 25.0 mol.% Gd₂O3, greater than or equal to 0.0 mol. % and less than or equal to20.0 mol. % Bi₂O3, greater than or equal to 0.0 mol. % and less than orequal to 20.0 mol. % ZrO₂, greater than or equal to 0.0 mol. % and lessthan or equal to 20.0 mol. % TeO₂, greater than or equal to 0.0 mol. %and less than or equal to 13.5 mol. % SiO₂, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % Al₂O₃, greater than orequal to 0.0 mol. % and less than or equal to 10.0 mol. % ThO₂, greaterthan or equal to 0.0 mol. % and less than or equal to 10.0 mol. % GeO₂,greater than or equal to 0.0 mol. % and less than or equal to 10.0 mol.% Ta₂O₅, greater than or equal to 0.0 mol. % and less than or equal to5.0 mol. % PbO, greater than or equal to 0.0 mol. % and less than orequal to 1.0 mol. % V₂O₅, greater than or equal to 0.0 at. % and lessthan or equal to 5.0 at. % F, greater than or equal to 0.0 at. % andless than or equal to 1.0 at. % Cl, greater than or equal to 0.0 at. %and less than or equal to 1.0 at. % Br, greater than or equal to 0.0 at.% and less than or equal to 1.0 at. % I, greater than or equal to 10.0mol. % RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, less than or equal to 40.0 mol. %WO₃+TiO₂, less than or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO and mayoptionally contain P₂O₅, wherein the composition of the componentssatisfies the conditions: TiO₂−SiO₂ [mol. %]≥7.5 and B₂O₃+SiO₂−P₂O₅[mol.%]≥0.00, and the glass satisfies the conditions: 1.9≤P_(n)≤2.1 andP_(ref)−(0.269−0.12*T_(i))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(ref) is a refraction parameter, calculated from the glass compositionin terms of mol. % of the components according to the Formula (IV):

P_(ref)(cm³/g)=0.000087034*SiO₂−0.00012035*B₂O₃−0.0012566*La₂O₃+0.0011411*TiO₂−0.00031654*ZnO+0.000088066*CaO+0.0020444*Nb₂O₅−0.00023383*MgO−0.00086501*BaO−0.0004486*WO₃−0.0014114*Gd₂O₃−0.00023872*Y₂O₃−0.00031575*Ta₂O₅+0.00011894*Li₂O+0.00027178*Al₂O₃−0.000099802*Na₂O−0.00028391*GeO₂−0.00030531*SrO−0.00072061*Bi₂O₃−0.0010964*Yb₂O₃+0.00022839*K₂O−0.00086617*PbO+0.00027129*TeO₂+0.198,  (IV)

T_(i) is a value of transmittance index, calculated from the glasscomposition in terms of mol. % of the components according to theFormula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅),  (I)

where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, R₂O is a total sum of monovalent metal oxides, RO is a totalsum of divalent metal oxides, and an asterisk (*) means multiplication.

According to one more embodiment of the present disclosure, a glasscomprises a plurality of components, the glass having a composition ofthe components comprising greater than or equal to 1.0 mol. % and lessthan or equal to 40.0 mol. % WO₃, greater than or equal to 0.3 mol. %and less than or equal to 20.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 40.0 mol. % B₂O₃, greater than or equalto 0.0 mol. % and less than or equal to 35.0 mol. % La₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 35.0 mol. % Bi₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 35.0 mol.% ZnO, greater than or equal to 0.0 mol. % and less than or equal to25.0 mol. % Ta₂O₅, greater than or equal to 0.0 mol. % and less than orequal to 10.0 mol. % Al₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % ThO₂, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % TeO₂, greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. % V₂O₅, greater than or equalto 10.0 mol. % RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, greater than or equal to 0.0mol. % and less than or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 4.8 mol. % SiO₂+GeO₂ andmay optionally contain one or more components selected from P₂O₅, BaO,CaO, K₂O, Li₂O, MgO, Na₂O, PbO and SrO, wherein the composition of thecomponents satisfies the condition: B₂O₃+SiO₂−P₂O₅[mol. %]≥0.50, and theglass satisfies the conditions: 500≤P_(Tg)≤700, P_(d)<6.0 andP_(n)−(1.571+0.083*P_(d))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. %according to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(d) is a density parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (III):

P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)

P_(Tg) is a T_(g) parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (V):

P _(Tg)(°C.)=595.358−0.63217*B₂O₃−0.46552*SiO₂+1.1849*TiO₂+0.59610*Nb₂O₅−1.6293*WO₃+1.3877*ZrO₂+4.4090*La₂O₃+4.1695*Y₂O₃−5.0756*Bi₂O₃+0.55630*CaO−5.3892*PbO−4.2774*TeO₂+1.8497*Al₂O₃−0.40659*GeO₂−1.7011*ZnO−4.1520*Li₂O+3.0777*Gd₂O₃,  (V)

where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, and an asterisk (*) means multiplication.

These and other aspects, objects, and features of the present disclosurewill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot illustrating the relationship between the transmittanceindex T_(i) calculated according to formula (I) and the minimumwavelength corresponding to a total transmittance of at least 70% for aglass sample having a thickness of 10 mm (λ_(70%)) for some comparativeglasses.

FIG. 2 is a plot illustrating the relationship between the refractiveindex n_(d) and the refractive index parameter P_(n) calculated byformula (II) for some Comparative Glasses and some Exemplary Glassesaccording to an embodiment of the present disclosure.

FIG. 3 is a plot illustrating the relationship between the density atroom temperature d_(RT) and the density parameter P_(d) calculated byformula (III) for some Comparative Glasses and some Exemplary Glassesaccording to an embodiment of the present disclosure.

FIG. 4 is a plot illustrating the relationship between the refraction(n_(d)−1)/d_(RT) and the refraction parameter P_(ref) calculated byformula (IV) for some Comparative Glasses and some Exemplary Glassesaccording to an embodiment of the present disclosure.

FIG. 5 is a plot illustrating the relationship between the glasstransition temperature T_(g) and the T_(g) parameter P_(Tg) calculatedby formula (V) for some Comparative Glasses and some Exemplary Glassesaccording to an embodiment of the present disclosure.

FIG. 6 is a plot of an exemplary cooling schedule according to a “15 mintest” condition and a “2.5 min test” condition for some ExemplaryGlasses according to an embodiment of the present disclosure.

FIG. 7 is a plot illustrating the relationship between the liquidustemperature T_(liq) and the refractive index parameter P_(n) for someComparative Glasses and some Exemplary Glasses according to anembodiment of the present disclosure.

FIG. 8 is a plot illustrating the relationship between the liquidustemperature T_(liq) and the refractive index n_(d) for some ComparativeGlasses and some Exemplary Glasses according to an embodiment of thepresent disclosure.

FIG. 9 is a plot illustrating the relationship between the transmittanceindex T_(i) and the refraction parameter P_(ref) for some ComparativeGlasses and some Exemplary Glasses according to an embodiment of thepresent disclosure.

FIG. 10 is a plot illustrating the relationship between thetransmittance index T_(i) and the refractive index to density ratio(“refraction”) (n_(d)−1)/d_(RT) for some Comparative Glasses and someExemplary Glasses according to an embodiment of the present disclosure.

FIG. 11 is a plot illustrating the relationship between the densityparameter P_(d) and the refractive index parameter P_(n) for someComparative Glasses and some Exemplary Glasses according to anembodiment of the present disclosure.

FIG. 12 is a plot illustrating the relationship between the density atroom temperature d_(RT) and the refractive index at 587.56 nm n_(d) forsome Comparative Glasses and some Exemplary Glasses according to anembodiment of the present disclosure.

FIG. 13 illustrates the transmittance spectra for an exemplary glassaccording to an embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation andnot limitation, example embodiments disclosing specific details are setforth to provide a thorough understanding of various principles of thepresent disclosure. However, it will be apparent to one having ordinaryskill in the art, having had the benefit of the present disclosure, thatthe present disclosure may be practiced in other embodiments that departfrom the specific details disclosed herein. Moreover, descriptions ofwell-known devices, methods and materials may be omitted so as not toobscure the description of various principles of the present disclosure.Finally, wherever applicable, like reference numerals refer to likeelements.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps, or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat an order be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including, without limitation,matters of logic with respect to arrangement of steps or operationalflow; plain meaning derived from grammatical organization orpunctuation; the number or type of embodiments described in thespecification.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

Modifications of the disclosure will occur to those skilled in the artand to those who make or use the disclosure. Therefore, it is understoodthat the embodiments shown in the drawings and described above aremerely for illustrative purposes and not intended to limit the scope ofthe disclosure, which is defined by the following claims, as interpretedaccording to the principles of patent law, including the doctrine ofequivalents.

As used herein, the term “about” means that amounts, sizes,formulations, parameters, and other quantities and characteristics arenot and need not be exact, but may be approximate and/or larger orsmaller, as desired, reflecting tolerances, conversion factors, roundingoff, measurement error and the like, and other factors known to thoseskilled in the art. When the term “about” is used in describing a valueor an end-point of a range, the disclosure should be understood toinclude the specific value or end-point referred to. Whether or not anumerical value or end-point of a range in the specification recites“about,” the numerical value or end-point of a range is intended toinclude two embodiments: one modified by “about,” and one not modifiedby “about.” It will be further understood that the end-points of each ofthe ranges are significant both in relation to the other end-point, andindependently of the other end-point.

The term “formed from” can mean one or more of comprises, consistsessentially of, or consists of. For example, a component that is formedfrom a particular material can comprise the particular material, consistessentially of the particular material, or consist of the particularmaterial.

The terms “free” and “substantially free” are used interchangeablyherein to refer to an amount and/or an absence of a particular componentin a glass composition that is not intentionally added to the glasscomposition. It is understood that the glass composition may containtraces of a particular constituent component as a contaminant or a trampin an amount of less than 0.10 mol %.

As used herein, the term “tramp”, when used to describe a particularconstituent component in a glass composition, refers to a constituentcomponent that is not intentionally added to the glass composition andis present in an amount of less than 0.05 mol %. Tramp components may beunintentionally added to the glass composition as an impurity in anotherconstituent component and/or through migration of the tramp componentinto the composition during processing of the glass composition.

The symbol “*” means multiplication when used in any formula herein.

Unless otherwise specified, the term “glass” is used to refer to a glassmade from a glass composition disclosed herein.

The term “glass former” is used herein to refer to a component that,being solely present in the glass composition (i.e., without othercomponents, except for tramps), is able to form a glass when cooling themelt at a rate of not greater than about 200° C./min to about 300°C./min.

The term “modifier”, as used herein, refers to the oxides of monovalentor divalent metals, i.e., R₂O or RO, where “R” stands for a cation.Modifiers can be added to a glass composition to change the atomicstructure of the melt and the resulting glass. In some embodiments, themodifier may change the coordination numbers of cations present in theglass formers (e.g., boron in B₂O₃), which may result in forming a morepolymerized atomic network and, as a result, may provide better glassformation.

As used herein, the term “RO” refers to a total content of divalentmetal oxides, the term “R₂O” refers to a total content of monovalentmetal oxides, and the term “Alk₂O” refers to a total content of alkalimetal oxides. The term R₂O encompasses alkali metal oxides (Alk₂O), inaddition to other monovalent metal oxides, such as Ag₂O, Tl₂O, and Hg₂O,for example. As discussed below, in the present disclosure, a rare earthmetal oxide is referred to herein by its normalized formula (RE₂O₃) inwhich the rare earth metal has the redox state “+3,” and thus rare earthmetal oxides are not encompassed by the term RO.

As used herein, the term “rare earth metals” refers to the metals listedin the Lanthanide Series of the IUPAC Periodic Table, plus yttrium andscandium. As used herein, the term “rare earth metal oxides,” is used torefer to the oxides of rare earth metals in different redox states, suchas “+3” for lanthanum in La₂O₃, “+4” for cerium in CeO₂, “+2” foreuropium in EuO, etc. In general, the redox states of rare earth metalsin oxide glasses may vary and, in particular, the redox state may changeduring melting, based on the batch composition and/or the redoxconditions in the furnace where the glass is melted and/or heat-treated(e.g., annealed). Unless otherwise specified, a rare earth metal oxideis referred to herein by its normalized formula in which the rare earthmetal has the redox state “+3.” Accordingly, in the case in which a rareearth metal having a redox state other than “+3” is added to the glasscomposition batch, the glass compositions are recalculated by adding orremoving some oxygen to maintain the stoichiometry. For example, whenCeO₂ (with cerium in redox state “+4”) is used as a batch component, theresulting as-batched composition is recalculated assuming that two molesof CeO₂ is equivalent to one mole of Ce₂O₃, and the resulting as-batchedcomposition is expressed in terms of Ce₂O₃. As used herein, the term“RE_(m)O_(n)” is used to refer to the total content of rare earth metaloxides in all redox states present in the as-batched composition, andthe term “RE₂O₃” is used to refer to the total content of rare earthmetal oxides in the as-batched composition when recalculated to “+3”redox state. The term “RE₂O₃” is also specified herein as “trivalentequivalent”.

Unless otherwise specified, all compositions are expressed in terms ofas-batched mole percent (mol %). References to “composition” or “glasscomposition” thus refer to composition expressed in terms of mol. % inthe as-batched state. As will be understood by those having ordinaryskill in the art, various melt constituents (e.g., fluorine, alkalimetals, boron, etc.) may be subject to different levels ofvolatilization (e.g., as a function of vapor pressure, melt time and/ormelt temperature) during melting of the constituents. As such, the term“about,” in relation to such constituents, is intended to encompassvalues within about 0.2 mol % when measuring final articles as comparedto the as-batched compositions provided herein. With the forgoing inmind, substantial compositional equivalence between final articles andas-batched compositions is expected. In some embodiments, whereindicated, the compositions may be expressed in terms of as-batchedpercent by weight of oxides (wt %).

Oxides and other constituents of the glass are referred to as“components”. Expressions combining components with the mathematicalsymbols “+” and “−” refer to sums and differences, respectively, of theas-batched composition of the components expressed in mol. %. Forexample, the expression “SiO₂+GeO₂” or the expression “SiO₂+GeO₂[mol.%]” means the sum of the components SiO₂ and GeO₂, each expressed inmol. %, in the as-batched composition. In another example, theexpression “B₂O₃+SiO₂−P₂O₅” or the expression “B₂O₃+SiO₂−P₂O₅[mol. %]”means the sum of the components B₂O₃+SiO₂ less the component P₂O₅, eachexpressed in mol. %, in the as-batched composition. If the expression ispreceded by an amount, the amount refers to the combined as-batchedcompositions of the components listed in the expression. For example,the expression “4.8 mol. % SiO₂+GeO₂” means that the combined amount ofthe components SiO₂ and GeO₂ in the as-batched composition is 4.8 mol. %and the expression “less than or equal to 4.8 mol. % SiO₂+GeO₂” meansthat the combined amount of the components of SiO₂ and GeO₂ in theas-batched composition is less than or equal to 4.8 mol. %.

In the case when fluorine or other halogen (chlorine, bromine, and/oriodine) is added to or is present in an oxide glass, the molecularrepresentation of the resulting as-batched composition may be expressedin different ways. In the present disclosure, the content of a halogenas a component, when present, is expressed in terms of atomic percent(at. %), which is determined based on the fraction of the halogen in atotal sum of all atoms in the as-batched composition multiplied by afactor of 100.

In the present disclosure, the following method of representation offluorine-containing compositions and concentration ranges is used. Theconcentration limits for all oxides (e.g. SiO₂, B₂O₃, Na₂O, etc.) arepresented under the assumption that the respective cations (such as, forexample, silicon [Si₄ ⁺], boron [B₃ ⁺], sodium [Na⁺], etc.) areinitially presented in the form of the corresponding oxides.

When fluorine is present as a sole halogen, for the purposes ofcalculating the concentration of components of the as-batchedcomposition, some part of the oxygen in the oxide is equivalentlyreplaced with fluorine (i.e. one atom of oxygen is replaced with twoatoms of fluorine). The fluorine is assumed to be present in the form ofsilicon fluoride (SiF₄); accordingly, the total sum of all oxides plusSiF₄ is assumed to be 100 mole percent or 100 weight percent in allcompositions. Analogous treatment of other halogens as sole halogens orcombinations of halogens applies.

The measured density values for the glasses reported herein weremeasured at room temperature in units of g/cm³ by the Archimedes methodin water with an uncertainty of 0.001 g/cm³. As used herein, densitymeasurements at room temperature (specified as d_(RT)) are indicated asbeing measured at 20° C. or 25° C., and encompass measurements obtainedat temperatures that may range from 20° C. to 25° C. It is understoodthat room temperature may vary between about 20° C. to about 25° C.,however, for the purposes of the present disclosure, the variation indensity within the temperature range of 20° C. to 25° C. is expected tobe less than the uncertainty of 0.001 g/cm³, and thus is not expected toimpact the room temperature density measurements reported herein.

As used herein, the term “refraction” refers to the relationship of therefractive index to the density according to the ratio:(n_(d)−1)/d_(RT), where the refractive index n_(d) is measured at 587.56nm and the density d_(RT) is measured in g/cm³ at room temperature. Theratio (n_(d)−1)/d_(RT), or refraction, may characterize the relationshipbetween the refractive index n_(d) and the density d_(RT). The higherthe refraction value, the higher the refractive index is at a givendensity.

As used herein, good glass forming ability refers to a resistance of themelt to devitrification as the melt cools. Glass forming ability can bemeasured by determining the critical cooling rate of the melt. The terms“critical cooling rate” or “v_(cr)” are used herein to refer to theminimum cooling rate at which a melt of a given composition forms aglass free of crystals visible under an optical microscope undermagnification from 100× to 500×. The critical cooling rate can be usedto measure the glass-forming ability of a composition, i.e., the abilityof the melt of a given glass composition to form glass when cooling.Generally speaking, the lower the critical cooling rate, the better theglass-forming ability.

The term “liquidus temperature” is used herein to refer to a temperatureabove which the glass composition is completely liquid with nocrystallization of constituent components of the glass. The liquidustemperature values reported herein were obtained by measuring samplesusing either DSC or by isothermal hold of samples wrapped in platinumfoil or in thermal gradient test in a platinum boat. For samplesmeasured using DSC, powdered samples were heated at 10 K/min to 1250° C.The end of the endothermal event corresponding to the melting ofcrystals was taken as the liquidus temperature. For the second technique(isothermal hold), a glass block (about 1 cm³) was put in platinum foiland placed in a furnace at a given temperature for 4 hours to 24 hours.The glass block was then observed under an optical microscope to checkfor crystals. For the third technique (thermal gradient test), about 10g of glass cullet was placed in a thin platinum boat and placed in afurnace at a given temperature for 4 hours to 24 hours. The glass blockwas then observed by a naked eye to check for crystals. For some ofExemplary Glasses of the present disclosure, several different testswere used to determine the liquidus temperature, and they providedessentially the same results.

As used herein, unless otherwise specified, the term “internaltransmittance” or τ_(int) is used to refer to the transmittance througha glass sample that is corrected for Fresnel losses. The term “totaltransmittance” or τ is used to refer to transmittance values for whichFresnel losses are not accounted for. Total transmittance of the glasssamples were measured on samples with two or three different thicknessesusing a Cary 5000 Spectrometer at wavelengths of from 250 nm to 2500 nm,at a resolution of 1 nm, and using an integrating sphere. The internaltransmittance values for 10 mm thick samples was calculated between 375nm and 1175 nm using the measured refractive index and the measuredtotal transmittance at those said different thicknesses. The totaltransmittance considers the loss by reflection of light on the surfaceof the sample. The wavelengths corresponding to specific values of totaltransmittance, such as, for example, 5% or 70%, are represented as λwith corresponding subscripts, such as λ_(5%) and λ_(70%), respectively.

The refractive index values reported herein were measured at roomtemperature (about 25° C.), unless otherwise specified. The refractiveindex values for a glass sample were measured using a Metricon Model2010 prism coupler refractometer with an uncertainty of about ±0.0002.Using the Metricon, the refractive index of a glass sample was measuredat two or more wavelengths of about 406 nm, 473 nm, 532 nm, 633 nm, 828nm, and 1064 nm. The measured dependence characterizes the dispersionand was then fitted with a Cauchy's law equation or Sellmeier equationto allow for calculation of the refractive index of the sample at agiven wavelength of interest between the measured wavelengths. The term“refractive index n_(d)” or “n_(d)” is used herein to refer to arefractive index calculated as described above at a wavelength of 587.56nm, which corresponds to the helium d-line wavelength. The term“refractive index n_(C)” or “n_(c)” is used herein to refer to arefractive index calculated as described above at a wavelength of 656.3nm. The term “refractive index n_(F)” or “n_(F)” is used herein to referto a refractive index calculated as described above at a wavelength of486.1 nm.

The term “refractive index n_(g)” or “n,” is used herein to refer to arefractive index calculated as described above at a wavelength of 435.8nm.

As used herein, the terms “high refractive index” or “high index” referto a refractive index value of a glass that is greater than or equal to1.80, unless otherwise indicated. Where indicated, embodiments of theterms “high refractive index” or “high index” refer to a refractiveindex value of a glass that is greater than or equal to 1.85, greaterthan or equal to 1.90, or greater than or equal to 1.95, or greater thanor equal to 2.00.

The terms “dispersion” and “optical dispersion” are used interchangeablyto refer to a difference or ratio of the refractive indices of a glasssample at predetermined wavelengths. One numerical measure of opticaldispersion reported herein is the Abbe number, which can be calculatedby the formula: v_(x)=(n_(x)−1)/(n_(F)−n_(C)), where “x” in the presentdisclosure stands for one of the commonly used wavelengths (for example,587.56 nm [d-line] for v_(d) or 589.3 nm [D-line] for V_(D)), n_(x) isthe refractive index at this wavelength (for example, n_(d) for v_(d)and n_(D) for v_(D)), and n_(F) and n_(C) are refractive indices at thewavelengths 486.1 nm (F-line) and 656.3 nm (C-line), respectively. Thenumerical values of v_(d) and v_(D) differ very slightly, mostly within±0.1% to ±0.2%. A higher Abbe number corresponds to a lower opticaldispersion.

The numerical value for an Abbe number corresponding to “highdispersion” or “low dispersion” may vary depending on the refractiveindices for which the Abbe number is calculated. In some cases, an Abbenumber corresponding to “low dispersion” for a high refractive indexglass may be lower than an Abbe number corresponding to “low dispersion”for a low refractive index glass. In other words, as the calculatedrefractive index value increases, the value of the Abbe numbercorresponding to low dispersion decreases. The same relates to “highdispersion” as well.

The term “α,” or “α₂₀₋₃₀₀,” as used herein, refers to the averagecoefficient of linear thermal expansion (CTE) of the glass compositionover a temperature range from 20° C. to 300° C. This property ismeasured by using a horizontal dilatometer (push-rod dilatometer) inaccordance with ASTM E228-11.

The numeric measure of a is a linear average value in a specifiedtemperature range (e.g., 20° C. to 300° C.) expressed as α=ΔL/(L₀ΔT),where L₀ is the linear size of a sample at room temperature, and L isthe change in the linear size (ΔL) in the measured temperature range ΔT.

The Young's elastic modulus E and the Poisson's ratio μ are measured byusing Resonant Ultrasound Spectroscopy, using a Quasar RUSpec 4000available from ITW Indiana Private Limited, Magnaflux Division.

The glass transition temperature (T_(g)) is measured by differentialscanning calorimeter (DSC) at the heating rate of 10 K/min after coolingin air.

The term “annealing point,” as used herein, refers to the temperaturedetermined according to ASTM C598-93(2013), at which the viscosity of aglass of a given glass composition is approximately 1013.2 poise.

Glass composition may include boron oxide (B₂O₃). According to someembodiments of the present disclosure, boron oxide may play a role of aglass former. As a glassformer, B₂O₃ may help to increase the liquidusviscosity and, therefore, protect a glass composition fromcrystallization. However, adding B₂O₃ to a glass composition may causeliquid-liquid phase separation, which may cause devitrification and/orreducing the transmittance of the resulting glass. Also, adding B₂O₃ tothe high-index glasses reduces the refractive index. Accordingly, theamount of boron oxide in glasses of the present disclosure is limited,or glasses may be substantially free of B₂O₃. In embodiments, the glasscomposition may contain boron oxide (B₂O₃) in an amount from greaterthan or equal to 0.0 mol. % to less than or equal to 41.0 mol. % and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition may contain B₂O₃ in an amount greater than orequal to 0.0 mol. %, greater than or equal to 1.0 mol. %, greater thanor equal to 5.0 mol. %, greater than or equal to 10.0 mol. %, greaterthan or equal to 20.0 mol. %, greater than or equal to 21.5 mol. %,greater than or equal to 23.0 mol. %, greater than or equal to 27.0 mol.%, greater than or equal to 30.0 mol. %, greater than or equal to 35.0mol. %, or greater than or equal to 40.0 mol. %. In some otherembodiments, the glass composition may contain B₂O₃ in an amount lessthan or equal to 41.0 mol. %, less than or equal to 40.0 mol. %, lessthan or equal to 35.0 mol. %, less than or equal to 34.5 mol. %, lessthan or equal to 33.0 mol. %, less than or equal to 30.0 mol. %, lessthan or equal to 20.0 mol. %, or less than or equal to 5.0 mol. %. Insome more embodiments, the glass composition may contain B₂O₃ in anamount greater than or equal to 0.0 mol. % and less than or equal to40.0 mol. %, greater than or equal to 1.0 mol. % and less than or equalto 40.0 mol. %, greater than or equal to 10.0 mol. % and less than orequal to 40.0 mol. %, greater than or equal to 20.0 mol. % and less thanor equal to 35.0 mol. %, greater than or equal to 21.5 mol. % and lessthan or equal to 34.5 mol. %, greater than or equal to 23.0 mol. % andless than or equal to 33.0 mol. %, greater than or equal to 27.05 mol. %and less than or equal to 33.24 mol. %, greater than or equal to 0.0mol. % and less than or equal to 41.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 5.0 mol. %, greater than or equalto 20.0 mol. % and less than or equal to 30.0 mol. %, greater than orequal to 30.0 mol. % and less than or equal to 33.0 mol. %, greater thanor equal to 34.5 mol. % and less than or equal to 35.0 mol. %, greaterthan or equal to 35.0 mol. % and less than or equal to 40.0 mol. %.

Glass composition may include silica (SiO₂). Silica may play a role ofan additional glass-former. Silica, as well as B₂O₃, may help toincrease the liquidus viscosity (viscosity at the liquidus temperature)and, therefore, protect a glass composition from crystallization.However, adding SiO₂ to a glass composition may cause liquid-liquidphase separation, which may cause devitrification and/or reducing thetransmittance of the resulting glass. Also, SiO₂ is a low refractiveindex component and makes it difficult to achieve high index glasses.Accordingly, the content of SiO₂ in the embodiments of the presentdisclosure is limited, or glasses may be substantially free of SiO₂. Inembodiments, the glass composition may contain silica (SiO₂) in anamount from greater than or equal to 0.0 mol. % to less than or equal to15.0 mol. % and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass composition may contain SiO₂ in an amountgreater than or equal to 0.0 mol. %, greater than or equal to 5.0 mol.%, greater than or equal to 9.0 mol. %, greater than or equal to 10.0mol. %, greater than or equal to 11.0 mol. %, or greater than or equalto 13.0 mol. %. In some other embodiments, the glass composition maycontain SiO₂ in an amount less than or equal to 15.0 mol. %, less thanor equal to 13.5 mol. %, less than or equal to 13.0 mol. %, less than orequal to 12.5 mol. %, less than or equal to 11.5 mol. %, less than orequal to 11.0 mol. %, less than or equal to 10.0 mol. %, less than orequal to 9.0 mol. %, less than or equal to 6.0 mol. %, less than orequal to 5.0 mol. %, less than or equal to 4.8 mol. %, or less than orequal to 4.5 mol. %. In some more embodiments, the glass composition maycontain SiO₂ in an amount greater than or equal to 0.0 mol. % and lessthan or equal to 15.0 mol. %, greater than or equal to 0.0 mol. % andless than or equal to 13.5 mol. %, greater than or equal to 0.0 mol. %and less than or equal to 12.5 mol. %, greater than or equal to 0.0 mol.% and less than or equal to 11.5 mol. %, greater than or equal to 0.0mol. % and less than or equal to 4.5 mol. %, greater than or equal to0.03 mol. % and less than or equal to 5.77 mol. %, greater than or equalto 4.5 mol. % and less than or equal to 4.8 mol. %, greater than orequal to 4.8 mol. % and less than or equal to 15.0 mol. %, greater thanor equal to 5.0 mol. % and less than or equal to 15.0 mol. %, greaterthan or equal to 6.0 mol. % and less than or equal to 9.0 mol. %.

Glass composition may include germania (GeO₂). Germania (GeO₂) providesexcellent ratio between the refractive index and density and does notreduce transmittance. However, germania is too expensive, and thus itmay make a glass composition not economical. Accordingly, the content ofgermania should be limited, or glass compositions may be free of GeO₂,or glasses may be substantially free of GeO₂. In embodiments, the glasscomposition may contain germania (GeO₂) in an amount from greater thanor equal to 0.0 mol. % to less than or equal to 10.0 mol. % and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition may contain GeO₂ in an amount greater than orequal to 0.0 mol. %, greater than or equal to 5.0 mol. %, greater thanor equal to 7.0 mol. %, greater than or equal to 8.0 mol. %, or greaterthan or equal to 9.0 mol. %. In some other embodiments, the glasscomposition may contain GeO₂ in an amount less than or equal to 10.0mol. %, less than or equal to 9.0 mol. %, less than or equal to 8.0 mol.%, less than or equal to 7.0 mol. %, less than or equal to 5.0 mol. %,less than or equal to 4.8 mol. %, or less than or equal to 0.5 mol. %.In some more embodiments, the glass composition may contain GeO₂ in anamount greater than or equal to 0.0 mol. % and less than or equal to10.0 mol. %, greater than or equal to 0.0 mol. % and less than or equalto 5.0 mol. %, greater than or equal to 0.0 mol. % and less than orequal to 0.5 mol. %, greater than or equal to 0.5 mol. % and less thanor equal to 10.0 mol. %, greater than or equal to 0.5 mol. % and lessthan or equal to 4.8 mol. %, greater than or equal to 4.8 mol. % andless than or equal to 10.0 mol. %, greater than or equal to 4.8 mol. %and less than or equal to 5.0 mol. %, greater than or equal to 5.0 mol.% and less than or equal to 10.0 mol. %, greater than or equal to 5.0mol. % and less than or equal to 7.0 mol. %.

Glass composition may include monovalent metal oxides (R₂O). Monovalentmetal oxides, such as alkali metal oxides (Li₂O, Na₂O, K₂O, Rb₂O andCs₂O) or others (for example, Ag₂O or Tl₂O) may help to betteraccommodate the index raisers, such as TiO₂, Nb₂O₅ or WO₃, in the glassstructure, which may cause increasing their solubility in a glass and,accordingly, indirectly cause increasing the refractive index at anacceptably low density.

In some embodiments, the glass composition may contain monovalent metaloxides R₂O in an amount greater than or equal to 0.0 mol. %, greaterthan or equal to 1.0 mol. %, greater than or equal to 2.0 mol. %,greater than or equal to 3.0 mol. %, or greater than or equal to 4.0mol. %. In some other embodiments, the glass composition may containmonovalent metal oxides R₂O in an amount less than or equal to 5.0 mol.%, less than or equal to 4.0 mol. %, less than or equal to 3.0 mol. %,less than or equal to 2.0 mol. %, or less than or equal to 1.0 mol. %.In some more embodiments, the glass composition may contain R₂O in anamount from 0.0 mol. % to 5.0 mol. %, from 0.0 mol. % to 4.0 mol. %,from 0.0 mol. % to 3.0 mol. %, from 0.0 mol. % to 2.0 mol. %, from 1.0mol. % to 5.0 mol. %, from 1.0 mol. % to 4.0 mol. %, from 1.0 mol. % to3.0 mol. %, from 1.0 mol. % to 2.0 mol. %, from 2.0 mol. % to 5.0 mol.%, from 2.0 mol. % to 4.0 mol. %, from 2.0 mol. % to 3.0 mol. %, from3.0 mol. % to 5.0 mol. %, from 3.0 mol. % to 4.0 mol. %, from 1.0 mol. %to 3.0 mol. %, from 2.0 mol. % to 4.0 mol. %, or from 1.0 mol. % to 4.0mol. %.

Glass composition may include divalent metal oxides (RO). Divalent metaloxides, such as alkaline earth metal oxides (BeO, MgO, CaO, SrO andBaO), zinc oxide (ZnO), cadmium oxide (CdO), lead oxide (PbO) andothers, being added to a glass, provide comparably high refractiveindexes, greater than those for most of monovalent oxides. Some divalentmetal oxides, such as, for example, CaO, SrO and ZnO, also providecomparably low density, therefore, increasing the ratio of therefractive index to density and, accordingly, improving the performanceof optical glasses in certain applications. In addition, divalent metaloxides may help to increase the solubility of high index components,such as TiO₂, Nb₂O₅ and WO₃, which indirectly leads to a furtherincrease in the refractive index at a comparable density. Also, somedivalent metal oxides, such as, for example, ZnO and MgO, providecomparably low thermal expansion coefficient, which may reduce thethermal stresses formed in the glass articles when cooling and,therefore, improve the quality of the glass articles. However, whenadding at high amounts, divalent metal oxides may cause crystallizationof refractory minerals from the melts or liquid-liquid phase separation,which may reduce the glass-forming ability of glasses. Accordingly, theamount of divalent metal oxides in glass compositions of the presentdisclosure is limited.

In some embodiments, the glass composition may contain divalent metaloxides RO in an amount greater than or equal to 0.0 mol. %, greater thanor equal to 1.0 mol. %, greater than or equal to 2.0 mol. %, greaterthan or equal to 3.0 mol. %, or greater than or equal to 4.0 mol. %. Insome other embodiments, the glass composition may contain divalent metaloxides RO in an amount less than or equal to 5.0 mol. %, less than orequal to 4.0 mol. %, less than or equal to 3.0 mol. %, less than orequal to 2.0 mol. %, or less than or equal to 1.0 mol. %. In some moreembodiments, the glass composition may contain RO in an amount from 0.0mol. % to 5.0 mol. %, from 0.0 mol. % to 4.0 mol. %, from 0.0 mol. % to3.0 mol. %, from 0.0 mol. % to 2.0 mol. %, from 1.0 mol. % to 5.0 mol.%, from 1.0 mol. % to 4.0 mol. %, from 1.0 mol. % to 3.0 mol. %, from1.0 mol. % to 2.0 mol. %, from 2.0 mol. % to 5.0 mol. %, from 2.0 mol. %to 4.0 mol. %, from 2.0 mol. % to 3.0 mol. %, from 3.0 mol. % to 5.0mol. %, from 3.0 mol. % to 4.0 mol. %, from 0 mol. % to 2.0 mol. %, from2.0 mol. % to 4.0 mol. %, or from 2.0 mol. % to 5.0 mol. %.

Glass composition may include zinc oxide (ZnO). Zinc oxide provides agood refractive index to density ratio and may sometimes increase thesolubility of titania, which indirectly increases the refractive indexof glasses. However, it was found that in some embodiments, at highconcentrations of ZnO, the glass-forming ability of the melt decreasesand the melt may tend to crystallize during cooling.

In some embodiments, the glass composition may contain ZnO in an amountgreater than or equal to 0.0 mol. %, greater than or equal to 5.0 mol.%, greater than or equal to 20.0 mol. %, greater than or equal to 25.0mol. %, or greater than or equal to 30.0 mol. %. In some otherembodiments, the glass composition may contain ZnO in an amount lessthan or equal to 35.0 mol. %, less than or equal to 30.0 mol. %, lessthan or equal to 25.0 mol. %, less than or equal to 20.0 mol. %, lessthan or equal to 5.0 mol. %, or less than or equal to 0.05 mol. %. Insome more embodiments, the glass composition may contain ZnO in anamount greater than or equal to 0.0 mol. % and less than or equal to35.0 mol. %, greater than or equal to 0.0 mol. % and less than or equalto 25.0 mol. %, greater than or equal to 0.0 mol. % and less than orequal to 0.05 mol. %, greater than or equal to 0.05 mol. % and less thanor equal to 35.0 mol. %, greater than or equal to 0.05 mol. % and lessthan or equal to 5.0 mol. %, greater than or equal to 5.0 mol. % andless than or equal to 35.0 mol. %, greater than or equal to 5.0 mol. %and less than or equal to 20.0 mol. %, greater than or equal to 20.0mol. % and less than or equal to 35.0 mol. %, greater than or equal to20.0 mol. % and less than or equal to 25.0 mol. %.

Glass composition may include barium oxide (BaO). Barium oxide mayincrease the solubility of high index components, such as TiO₂ andNb₂O₅, which may indirectly lead to a further increase in the refractiveindex at comparably low density. However, barium is a heavy element and,being added in a high amount, may increase the density of glass. Also,in high concentration, it may cause crystallization of such minerals asbarium titanate (BaTiO₃), barium niobate (BaNb₂O₆) and others.Accordingly, the amount of BaO in glasses of the present disclosure islimited, or glasses may be substantially free of BaO. In embodiments,the glass composition may contain barium oxide (BaO) in an amount fromgreater than or equal to 0.0 mol. % to less than or equal to 10.0 mol. %and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass composition may contain BaO in an amount greaterthan or equal to 0.0 mol. %, or greater than or equal to 5.0 mol. %. Insome other embodiments, the glass composition may contain BaO in anamount less than or equal to 10.0 mol. %, less than or equal to 5.0 mol.%, less than or equal to 4.6 mol. %, less than or equal to 4.0 mol. %,or less than or equal to 1.6 mol. %. In some more embodiments, the glasscomposition may contain BaO in an amount greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 4.6 mol. %, greater than or equalto 0.0 mol. % and less than or equal to 4.0 mol. %, greater than orequal to 0.01 mol. % and less than or equal to 1.6 mol. %, greater thanor equal to 0.0 mol. % and less than or equal to 10.0 mol. %, greaterthan or equal to 0.0 mol. % and less than or equal to 1.6 mol. %,greater than or equal to 1.6 mol. % and less than or equal to 10.0 mol.%, greater than or equal to 1.6 mol. % and less than or equal to 4.0mol. %.

Glass composition may include lead oxide (PbO). Lead oxide provides veryhigh refractive index, but also significantly increases the density.Also, PbO may cause ecological concern. For these reasons, the contentof PbO in glasses of the present disclosure should be limited, orglasses may be substantially free of PbO. In embodiments, the glasscomposition may contain lead oxide (PbO) in an amount from greater thanor equal to 0.0 mol. % to less than or equal to 10.0 mol. % and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition may contain PbO in an amount greater than or equalto 0.0 mol. %, greater than or equal to 5.0 mol. %, greater than orequal to 7.0 mol. %, greater than or equal to 8.0 mol. %, or greaterthan or equal to 9.0 mol. %. In some other embodiments, the glasscomposition may contain PbO in an amount less than or equal to 10.0 mol.%, less than or equal to 9.0 mol. %, less than or equal to 8.0 mol. %,less than or equal to 7.0 mol. %, less than or equal to 5.0 mol. %, orless than or equal to 0.5 mol. %. In some more embodiments, the glasscomposition may contain PbO in an amount greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 0.5 mol. %, greater than or equalto 0.0 mol. % and less than or equal to 10.0 mol. %, greater than orequal to 0.5 mol. % and less than or equal to 10.0 mol. %, greater thanor equal to 0.5 mol. % and less than or equal to 5.0 mol. %, greaterthan or equal to 5.0 mol. % and less than or equal to 10.0 mol. %,greater than or equal to 5.0 mol. % and less than or equal to 7.0 mol.%, greater than or equal to 7.0 mol. % and less than or equal to 10.0mol. %, greater than or equal to 7.0 mol. % and less than or equal to8.0 mol. %.

In some embodiments, the glass composition may contain rare earth metaloxides in trivalent equivalent RE₂O₃ in an amount greater than or equalto 0.0 mol. %, greater than or equal to 0.25 mol. %, greater than orequal to 0.5 mol. %, or greater than or equal to 0.75 mol. %.

Glass composition may include lanthanum oxide (La₂O₃). Lanthanum oxideis one of the cheapest oxides providing high refractive indexes withoutsignificant loss of transmittance in visible range. Also, addition ofLa₂O₃ may reduce the risk of phase separation. However, La₂O₃ provideshigher density than other high-index components, such as, for example,TiO₂, Nb₂O₅ or WO₃. Also, when added in high amounts, it may causecrystallization of refractory species. For this reason, the content ofLa₂O₃ in the glasses of the present disclosure should be limited. Inembodiments, the glass composition may contain lanthanum oxide (La₂O₃)in an amount from greater than or equal to 0.0 mol. % to less than orequal to 35.0 mol. % and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition may contain La₂O₃ inan amount greater than or equal to 0.0 mol. %, greater than or equal to5.0 mol. %, greater than or equal to 10.0 mol. %, greater than or equalto 13.0 mol. %, greater than or equal to 14.5 mol. %, greater than orequal to 15.0 mol. %, greater than or equal to 20.0 mol. %, greater thanor equal to 25.0 mol. %, or greater than or equal to 30.0 mol. %. Insome other embodiments, the glass composition may contain La₂O₃ in anamount less than or equal to 35.0 mol. %, less than or equal to 30.0mol. %, less than or equal to 25.0 mol. %, less than or equal to 24.0mol. %, less than or equal to 22.5 mol. %, less than or equal to 21.4mol. %, less than or equal to 20.0 mol. %, less than or equal to 5.0mol. %, or less than or equal to 1.0 mol. %. In some more embodiments,the glass composition may contain La₂O₃ in an amount greater than orequal to 0.0 mol. % and less than or equal to 35.0 mol. %, greater thanor equal to 0.0 mol. % and less than or equal to 25.0 mol. %, greaterthan or equal to 10.0 mol. % and less than or equal to 25.0 mol. %,greater than or equal to 13.0 mol. % and less than or equal to 24.0 mol.%, greater than or equal to 14.5 mol. % and less than or equal to 22.5mol. %, greater than or equal to 15.0 mol. % and less than or equal to25.0 mol. %, greater than or equal to 19.97 mol. % and less than orequal to 21.43 mol. %, greater than or equal to 0.0 mol. % and less thanor equal to 1.0 mol. %, greater than or equal to 1.0 mol. % and lessthan or equal to 5.0 mol. %, greater than or equal to 5.0 mol. % andless than or equal to 35.0 mol. %, greater than or equal to 20.0 mol. %and less than or equal to 21.4 mol. %, greater than or equal to 21.4mol. % and less than or equal to 35.0 mol. %, greater than or equal to21.4 mol. % and less than or equal to 22.5 mol. %, greater than or equalto 22.5 mol. % and less than or equal to 24.0 mol. %.

In embodiments, the glass composition may contain yttria (Y₂O₃) in anamount from greater than or equal to 0.0 mol. % to less than or equal to10.0 mol. % and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass composition may contain Y₂O₃ in an amountgreater than or equal to 0.0 mol. %, greater than or equal to 5.0 mol.%, greater than or equal to 7.0 mol. %, greater than or equal to 8.0mol. %, or greater than or equal to 9.0 mol. %. In some otherembodiments, the glass composition may contain Y₂O₃ in an amount lessthan or equal to 10.0 mol. %, less than or equal to 9.0 mol. %, lessthan or equal to 8.0 mol. %, less than or equal to 7.5 mol. %, less thanor equal to 7.0 mol. %, less than or equal to 6.5 mol. %, less than orequal to 5.75 mol. %, less than or equal to 5.0 mol. %, or less than orequal to 1.0 mol. %. In some more embodiments, the glass composition maycontain Y₂O₃ in an amount greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. %, greater than or equal to 0.0 mol. % andless than or equal to 7.5 mol. %, greater than or equal to 0.0 mol. %and less than or equal to 6.5 mol. %, greater than or equal to 0.0 mol.% and less than or equal to 5.75 mol. %, greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. %, greater than or equal to0.38 mol. % and less than or equal to 5.02 mol. %, greater than or equalto 0.0 mol. % and less than or equal to 1.0 mol. %, greater than orequal to 1.0 mol. % and less than or equal to 5.0 mol. %, greater thanor equal to 5.0 mol. % and less than or equal to 10.0 mol. %, greaterthan or equal to 5.0 mol. % and less than or equal to 5.75 mol. %,greater than or equal to 5.75 mol. % and less than or equal to 6.5 mol.%.

In some embodiments, the glass composition may contain gadolinium oxide(Gd₂O₃) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 5.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containGd₂O₃ in an amount greater than or equal to 0.0 mol. %, or greater thanor equal to 2.5 mol. %. In some other embodiments, the glass compositionmay contain Gd₂O₃ in an amount less than or equal to 5.0 mol. %, lessthan or equal to 5.0 mol. %, less than or equal to 2.5 mol. %, or lessthan or equal to 1.0 mol. %. In some more embodiments, the glasscomposition may contain Gd₂O₃ in an amount greater than or equal to 0.0mol. % and less than or equal to 25.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 1.0 mol. %, greater than or equalto 1.0 mol. % and less than or equal to 25.0 mol. %, greater than orequal to 1.0 mol. % and less than or equal to 2.5 mol. %, greater thanor equal to 2.5 mol. % and less than or equal to 25.0 mol. %, greaterthan or equal to 2.5 mol. % and less than or equal to 5.0 mol. %.

Glass composition may include alumina (Al₂O₃). Alumina may increase theviscosity of glassforming melts at high temperature, which may reducethe critical cooling rate and improve the glassforming ability. However,addition of Al₂O₃ may cause crystallization of refractory minerals, suchas aluminum titanate (Al₂TiO₅), aluminum niobate (AlNbO₄) and others, inthe melts when cooling. Accordingly, the amount of Al₂O₃ in glasses ofthe present disclosure is limited, or glasses may be substantially freeof Al₂O₃. In embodiments, the glass composition may contain alumina(Al₂O₃) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 10.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containAl₂O₃ in an amount greater than or equal to 0.0 mol. %, greater than orequal to 5.0 mol. %, greater than or equal to 7.0 mol. %, greater thanor equal to 8.0 mol. %, or greater than or equal to 9.0 mol. %. In someother embodiments, the glass composition may contain Al₂O₃ in an amountless than or equal to 10.0 mol. %, less than or equal to 9.0 mol. %,less than or equal to 8.0 mol. %, less than or equal to 7.0 mol. %, orless than or equal to 5.0 mol. %. In some more embodiments, the glasscomposition may contain Al₂O₃ in an amount greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 5.0 mol. %, greater than or equalto 5.0 mol. % and less than or equal to 10.0 mol. %.

In embodiments, the glass composition may contain molybdenum oxide(MoO₃) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 10.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containMoO₃ in an amount greater than or equal to 0.0 mol. %, greater than orequal to 5.0 mol. %, greater than or equal to 7.0 mol. %, greater thanor equal to 8.0 mol. %, or greater than or equal to 9.0 mol. %. In someother embodiments, the glass composition may contain MoO₃ in an amountless than or equal to 10.0 mol. %, less than or equal to 9.0 mol. %,less than or equal to 8.0 mol. %, less than or equal to 7.0 mol. %, lessthan or equal to 5.0 mol. %, or less than or equal to 3.0 mol. %. Insome more embodiments, the glass composition may contain MoO₃ in anamount greater than or equal to 0.0 mol. % and less than or equal to 3.0mol. %, greater than or equal to 0.0 mol. % and less than or equal to10.0 mol. %.

Glass composition may include tellurium oxide (TeO₂). Tellurium oxidegenerally works like below-described bismuth oxide; in addition, TeO₂ isvery expensive, which may make the cost of starting materialsunacceptably high. Accordingly, the content of tellurium oxide should belimited, or glass compositions may be free of TeO₂. In embodiments, theglass composition may contain tellurium oxide (TeO₂) in an amount fromgreater than or equal to 0.0 mol. % to less than or equal to 20.0 mol. %and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass composition may contain TeO₂ in an amount greaterthan or equal to 0.0 mol. %, greater than or equal to 5.0 mol. %,greater than or equal to 10.0 mol. %, greater than or equal to 14.0 mol.%, greater than or equal to 16.0 mol. %, or greater than or equal to18.0 mol. %. In some other embodiments, the glass composition maycontain TeO₂ in an amount less than or equal to 20.0 mol. %, less thanor equal to 18.0 mol. %, less than or equal to 16.0 mol. %, less than orequal to 14.0 mol. %, less than or equal to 10.0 mol. %, less than orequal to 5.0 mol. %, or less than or equal to 2.0 mol. %. In some moreembodiments, the glass composition may contain TeO₂ in an amount greaterthan or equal to 0.0 mol. % and less than or equal to 20.0 mol. %,greater than or equal to 0.0 mol. % and less than or equal to 10.0 mol.%, greater than or equal to 0.0 mol. % and less than or equal to 2.0mol. %.

Glass composition may include vanadia (V₂O₅). Vanadia provides thehighest ratio of the refractive index to density among all oxides.However, vanadia may cause undesirable dark coloring. For these reasons,the content of vanadia in the glasses of the present disclosure islimited, or glass compositions may be free of V₂O₅. In embodiments, theglass composition may contain vanadia (V₂O₅) in an amount from greaterthan or equal to 0.0 mol. % to less than or equal to 5.0 mol. % and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition may contain V₂O₅ in an amount greater than orequal to 0.0 mol. %, or greater than or equal to 2.5 mol. %. In someother embodiments, the glass composition may contain V₂O₅ in an amountless than or equal to 5.0 mol. %, less than or equal to 2.5 mol. %, lessthan or equal to 1.0 mol. %, or less than or equal to 0.1 mol. %. Insome more embodiments, the glass composition may contain V₂O₅ in anamount greater than or equal to 0.0 mol. % and less than or equal to 5.0mol. %, greater than or equal to 0.0 mol. % and less than or equal to1.0 mol. %, greater than or equal to 0.0 mol. % and less than or equalto 0.1 mol. %.

In embodiments, the glass composition may contain thorium oxide (ThO₂)in an amount from greater than or equal to 0.0 mol. % to less than orequal to 10.0 mol. % and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition may contain ThO₂ inan amount greater than or equal to 0.0 mol. %, greater than or equal to5.0 mol. %, greater than or equal to 7.0 mol. %, greater than or equalto 8.0 mol. %, or greater than or equal to 9.0 mol. %. In some otherembodiments, the glass composition may contain ThO₂ in an amount lessthan or equal to 10.0 mol. %, less than or equal to 9.0 mol. %, lessthan or equal to 8.0 mol. %, less than or equal to 7.0 mol. %, or lessthan or equal to 5.0 mol. %. In some more embodiments, the glasscomposition may contain ThO₂ in an amount greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. %, greater than or equal to0.0 mol. % and less than or equal to 5.0 mol. %.

Glass composition may include tantalum oxide (Ta₂O₅). Tantalum oxideincreases the refractive index while maintaining an acceptable densitywithout reducing the blue transmittance. However, Ta₂O₅ may causecrystallization of refractory minerals. Accordingly, the content oftantalum oxide should be limited, or glass compositions may be free ofTa₂O₅. In embodiments, the glass composition may contain tantalum oxide(Ta₂O₅) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 25.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containTa₂O₅ in an amount greater than or equal to 0.0 mol. %, greater than orequal to 5.0 mol. %, greater than or equal to 10.0 mol. %, greater thanor equal to 19.0 mol. %, greater than or equal to 20.0 mol. %, greaterthan or equal to 21.0 mol. %, or greater than or equal to 23.0 mol. %.In some other embodiments, the glass composition may contain Ta₂O₅ in anamount less than or equal to 25.0 mol. %, less than or equal to 23.0mol. %, less than or equal to 21.0 mol. %, less than or equal to 20.0mol. %, less than or equal to 19.0 mol. %, less than or equal to 10.0mol. %, less than or equal to 5.0 mol. %, or less than or equal to 2.0mol. %. In some more embodiments, the glass composition may containTa₂O₅ in an amount greater than or equal to 0.0 mol. % and less than orequal to 25.0 mol. %, greater than or equal to 0.0 mol. % and less thanor equal to 10.0 mol. %, greater than or equal to 0.0 mol. % and lessthan or equal to 2.0 mol. %.

Glass composition may include zirconia (ZrO₂). Zirconia can increase therefractive index while maintaining an acceptably low density. ZrO₂ canalso increase the viscosity of the melt, which may help to protect themelt from crystallization. ZrO₂ does not introduce coloring in the glassin the visible and near-UV ranges, which may help to maintain a hightransmittance of the glass. However, high concentrations of zirconia maycause crystallization of refractory minerals, such as zirconia (ZrO₂),zircon (ZrSiO₄), calcium zirconate (CaZrO₃) and others, which maydecrease the glass forming ability of the melt. In embodiments, theglass composition may contain zirconia (ZrO₂) in an amount from greaterthan or equal to 0.0 mol. % to less than or equal to 20.0 mol. % and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition may contain ZrO₂ in an amount greater than orequal to 0.0 mol. %, greater than or equal to 0.3 mol. %, greater thanor equal to 0.5 mol. %, greater than or equal to 1.75 mol. %, greaterthan or equal to 5.0 mol. %, greater than or equal to 6.99 mol. %,greater than or equal to 10.0 mol. %, greater than or equal to 14.0 mol.%. In some other embodiments, the glass composition may contain ZrO₂ inan amount less than or equal to 20.0 mol. %, less than or equal to 18.0mol. %, less than or equal to 16.0 mol. %, less than or equal to 14.0mol. %, less than or equal to 10.0 mol. %, less than or equal to 8.0mol. %, less than or equal to 7.5 mol. %, less than or equal to 7.25mol. %, less than or equal to 7.0 mol. %, or less than or equal to 5.0mol. %. In some more embodiments, the glass composition may contain ZrO₂in an amount greater than or equal to 0.0 mol. % and less than or equalto 10.0 mol. %, greater than or equal to 0.0 mol. % and less than orequal to 7.5 mol. %, greater than or equal to 0.3 mol. % and less thanor equal to 20.0 mol. %, greater than or equal to 0.5 mol. % and lessthan or equal to 8.0 mol. %, greater than or equal to 1.75 mol. % andless than or equal to 7.25 mol. %, greater than or equal to 6.99 mol. %and less than or equal to 7.0 mol. %, greater than or equal to 0.0 mol.% and less than or equal to 20.0 mol. %, greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. %, greater than or equal to5.0 mol. % and less than or equal to 7.0 mol. %, greater than or equalto 7.0 mol. % and less than or equal to 7.25 mol. %, greater than orequal to 7.5 mol. % and less than or equal to 8.0 mol. %, greater thanor equal to 8.0 mol. % and less than or equal to 10.0 mol. %, greaterthan or equal to 10.0 mol. % and less than or equal to 20.0 mol. %,greater than or equal to 10.0 mol. % and less than or equal to 14.0 mol.%.

Glass composition may include bismuth oxide (Bi₂O₃). Bi₂O₃ provides veryhigh refractive index, ut leads to increases in density. However, it maydecrease the viscosity of melts at high temperatures, which may causecrystallization of the melts when cooling. Accordingly, the content ofbismuth oxide should be limited, or glass compositions may be free ofBi₂O₃. In embodiments, the glass composition may contain bismuth oxide(Bi₂O₃) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 35.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containBi₂O₃ in an amount greater than or equal to 0.0 mol. %, greater than orequal to 5.0 mol. %, greater than or equal to 20.0 mol. %, greater thanor equal to 25.0 mol. %, or greater than or equal to 30.0 mol. %. Insome other embodiments, the glass composition may contain Bi₂O₃ in anamount less than or equal to 35.0 mol. %, less than or equal to 30.0mol. %, less than or equal to 25.0 mol. %, less than or equal to 20.0mol. %, less than or equal to 10.0 mol. %, less than or equal to 7.5mol. %, less than or equal to 7.0 mol. %, or less than or equal to 5.0mol. %. In some more embodiments, the glass composition may containBi₂O₃ in an amount greater than or equal to 0.0 mol. % and less than orequal to 35.0 mol. %, greater than or equal to 0.0 mol. % and less thanor equal to 20.0 mol. %, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. %, greater than or equal to 0.0 mol. % andless than or equal to 7.5 mol. %, greater than or equal to 0.0 mol. %and less than or equal to 7.0 mol. %.

Glass composition may include niobia (Nb₂O₅). Niobia can be used toincrease the refractive index of glass while maintaining a low density.However, niobia can introduce a yellow coloring to the glass that cannotbe bleached in the same manner as titania, which can result in a loss oftransmittance, particularly in the blue and UV range. Niobia may causecrystallization and/or phase separation of the melt. In someembodiments, the glasses may be substantially free of Nb₂O₅. Inembodiments, the glass composition may contain niobia (Nb₂O₅) in anamount from greater than or equal to 0.0 mol. % to less than or equal to50.0 mol. % and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass composition may contain Nb₂O₅ in anamount greater than or equal to 0.0 mol. %, greater than or equal to 0.3mol. %, greater than or equal to 1.0 mol. %, greater than or equal to3.0 mol. %, greater than or equal to 4.5 mol. %, greater than or equalto 5.0 mol. %, greater than or equal to 6.0 mol. %, greater than orequal to 7.8 mol. %, greater than or equal to 10.0 mol. %, greater thanor equal to 25.0 mol. %, greater than or equal to 35.0 mol. %, greaterthan or equal to 40.0 mol. %, or greater than or equal to 45.0 mol. %.In some other embodiments, the glass composition may contain Nb₂O₅ in anamount less than or equal to 50.0 mol. %, less than or equal to 45.0mol. %, less than or equal to 40.0 mol. %, less than or equal to 35.0mol. %, less than or equal to 25.0 mol. %, less than or equal to 20.0mol. %, less than or equal to 19.5 mol. %, less than or equal to 19.0mol. %, less than or equal to 18.0 mol. %, less than or equal to 16.5mol. %, less than or equal to 15.0 mol. %, or less than or equal to 10.0mol. %. In some more embodiments, the glass composition may containNb₂O₅ in an amount greater than or equal to 0.3 mol. % and less than orequal to 50.0 mol. %, greater than or equal to 0.3 mol. % and less thanor equal to 20.0 mol. %, greater than or equal to 0.3 mol. % and lessthan or equal to 19.5 mol. %, greater than or equal to 1.0 mol. % andless than or equal to 19.0 mol. %, greater than or equal to 3.0 mol. %and less than or equal to 20.0 mol. %, greater than or equal to 4.5 mol.% and less than or equal to 18.0 mol. %, greater than or equal to 6.0mol. % and less than or equal to 16.5 mol. %, greater than or equal to7.79 mol. % and less than or equal to 15.0 mol. %, greater than or equalto 0.0 mol. % and less than or equal to 50.0 mol. %, greater than orequal to 0.0 mol. % and less than or equal to 10.0 mol. %, greater thanor equal to 10.0 mol. % and less than or equal to 15.0 mol. %, greaterthan or equal to 15.0 mol. % and less than or equal to 50.0 mol. %,greater than or equal to 16.5 mol. % and less than or equal to 18.0 mol.%, greater than or equal to 18.0 mol. % and less than or equal to 50.0mol. %, greater than or equal to 18.0 mol. % and less than or equal to19.0 mol. %, greater than or equal to 19.0 mol. % and less than or equalto 19.5 mol. %, greater than or equal to 19.5 mol. % and less than orequal to 50.0 mol. %.

Glass composition may include titania (TiO₂). The levels of TiO₂ and/orNb₂O₅ that are typically used in glasses to increase refractive indextend to decrease the transmittance in the near-UV region and shift theUV cut-off to higher wavelengths. Accordingly, the amount of TiO₂ islimited. In embodiments, the glass composition may contain titania(TiO₂) in an amount from greater than or equal to 0.0 mol. % to lessthan or equal to 50.0 mol. % and all ranges and sub-ranges between theforegoing values. In some embodiments, the glass composition may containTiO₂ in an amount greater than or equal to 0.0 mol. %, greater than orequal to 0.3 mol. %, greater than or equal to 1.0 mol. %, greater thanor equal to 5.0 mol. %, greater than or equal to 6.0 mol. %, greaterthan or equal to 7.5 mol. %, greater than or equal to 8.0 mol. %,greater than or equal to 10.0 mol. %, greater than or equal to 25.0 mol.%, greater than or equal to 35.0 mol. %, greater than or equal to 40.0mol. %, or greater than or equal to 45.0 mol. %. In some otherembodiments, the glass composition may contain TiO₂ in an amount lessthan or equal to 50.0 mol. %, less than or equal to 45.0 mol. %, lessthan or equal to 40.0 mol. %, less than or equal to 35.0 mol. %, lessthan or equal to 30.0 mol. %, less than or equal to 28.0 mol. %, lessthan or equal to 25.0 mol. %, less than or equal to 22.0 mol. %, lessthan or equal to 20.0 mol. %, less than or equal to 19.0 mol. %, lessthan or equal to 17.0 mol. %, or less than or equal to 10.0 mol. %. Insome more embodiments, the glass composition may contain TiO₂ in anamount greater than or equal to 0.3 mol. % and less than or equal to50.0 mol. %, greater than or equal to 0.3 mol. % and less than or equalto 30.0 mol. %, greater than or equal to 1.0 mol. % and less than orequal to 19.0 mol. %, greater than or equal to 5.0 mol. % and less thanor equal to 25.0 mol. %, greater than or equal to 6.0 mol. % and lessthan or equal to 22.0 mol. %, greater than or equal to 7.5 mol. % andless than or equal to 28.0 mol. %, greater than or equal to 8.0 mol. %and less than or equal to 20.0 mol. %, greater than or equal to 10.0mol. % and less than or equal to 16.98 mol. %, greater than or equal to0.0 mol. % and less than or equal to 50.0 mol. %, greater than or equalto 0.0 mol. % and less than or equal to 10.0 mol. %, greater than orequal to 17.0 mol. % and less than or equal to 19.0 mol. %, greater thanor equal to 19.0 mol. % and less than or equal to 20.0 mol. %, greaterthan or equal to 22.0 mol. % and less than or equal to 50.0 mol. %,greater than or equal to 22.0 mol. % and less than or equal to 25.0 mol.%, greater than or equal to 25.0 mol. % and less than or equal to 28.0mol. %.

Glass composition may include tungsten oxide (WO₃). WO₃ provides highrefractive index without significantly increasing density or causingundesirable coloring. Also, it was empirically found that addition ofWO₃ to glass composition may decrease the liquidus temperature, whichallows melting such glasses at lower temperatures, that, in turn, mayincrease the transmittance of such glasses. Also, addition of WO₃ maydecrease the glass transition temperature T_(g), which allows formingthese glasses at lower temperatures. At high concentrations of WO₃, theliquidus temperature tends to increase, and the viscosity at theliquidus temperature drops, making it difficult to avoid crystallizationof melts when cooling. Accordingly, the content of WO₃ should belimited, or glass compositions may be free of WO₃. In embodiments, theglass composition may contain tungsten oxide (WO₃) in an amount fromgreater than or equal to 0.0 mol. % to less than or equal to 40.0 mol. %and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass composition may contain WO₃ in an amount greaterthan or equal to 0.0 mol. %, greater than or equal to 1.0 mol. %,greater than or equal to 2.0 mol. %, greater than or equal to 3.0 mol.%, greater than or equal to 5.0 mol. %, greater than or equal to 6.0mol. %, greater than or equal to 9.0 mol. %, greater than or equal to20.0 mol. %, greater than or equal to 25.0 mol. %, greater than or equalto 30.0 mol. %, or greater than or equal to 35.0 mol. %. In some otherembodiments, the glass composition may contain WO₃ in an amount lessthan or equal to 40.0 mol. %, less than or equal to 35.0 mol. %, lessthan or equal to 30.0 mol. %, less than or equal to 26.0 mol. %, lessthan or equal to 25.0 mol. %, less than or equal to 23.0 mol. %, lessthan or equal to 20.0 mol. %, or less than or equal to 5.0 mol. %. Insome more embodiments, the glass composition may contain WO₃ in anamount greater than or equal to 0.0 mol. % and less than or equal to35.0 mol. %, greater than or equal to 0.0 mol. % and less than or equalto 30.0 mol. %, greater than or equal to 1.0 mol. % and less than orequal to 40.0 mol. %, greater than or equal to 2.0 mol. % and less thanor equal to 26.0 mol. %, greater than or equal to 3.0 mol. % and lessthan or equal to 35.0 mol. %, greater than or equal to 5.0 mol. % andless than or equal to 23.0 mol. %, greater than or equal to 8.68 mol. %and less than or equal to 20.45 mol. %, greater than or equal to 0.0mol. % and less than or equal to 40.0 mol. %, greater than or equal to5.0 mol. % and less than or equal to 40.0 mol. %, greater than or equalto 5.0 mol. % and less than or equal to 20.0 mol. %, greater than orequal to 23.0 mol. % and less than or equal to 40.0 mol. %, greater thanor equal to 23.0 mol. % and less than or equal to 25.0 mol. %, greaterthan or equal to 25.0 mol. % and less than or equal to 26.0 mol. %,greater than or equal to 26.0 mol. % and less than or equal to 30.0 mol.%, greater than or equal to 30.0 mol. % and less than or equal to 35.0mol. %.

Glass composition may include fluorine (F). Adding fluorine to a glasscomposition is known to provide lower optical dispersion, which mayimprove the image quality. Also, fluorine can in some cases decrease theliquidus temperature, preventing a glass article from crystallizationwhen cooling the melt.

However, fluorine may be a subject of ecological concern. For thatreason, the content of fluorine is limited, or glasses are free offluorine. In embodiments, the glass composition may contain fluorine (F)in an amount from greater than or equal to 0.0 at. % to less than orequal to 5.0 at. % and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition may contain F in anamount greater than or equal to 0.0 at. %, or greater than or equal to2.5 at. %. In some other embodiments, the glass composition may containF in an amount less than or equal to 5.0 at. %, less than or equal to2.5 at. %, or less than or equal to 0.1 at. %.

In embodiments, the glass composition may contain chlorine (Cl) in anamount from greater than or equal to 0.0 at. % to less than or equal to1.0 at. % and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass composition may contain C1 in an amountgreater than or equal to 0.0 at. %, or greater than or equal to 0.5 at.%. In some other embodiments, the glass composition may contain C1 in anamount less than or equal to 1.0 at. % or less than or equal to 0.5 at.%.

In embodiments, the glass composition may contain bromine (Br) in anamount from greater than or equal to 0.0 at. % to less than or equal to1.0 at. % and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass composition may contain Br in an amountgreater than or equal to 0.0 at. %, or greater than or equal to 0.5 at.%. In some other embodiments, the glass composition may contain Br in anamount less than or equal to 1.0 at. % or less than or equal to 0.5 at.%.

In embodiments, the glass composition may contain iodine (I) in anamount from greater than or equal to 0.0 at. % to less than or equal to1.0 at. % and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass composition may contain I in an amountgreater than or equal to 0.0 at. %, or greater than or equal to 0.5 at.%. In some other embodiments, the glass composition may contain I in anamount less than or equal to 1.0 at. % or less than or equal to 0.5 at.%.

In some other embodiments, the glass composition may have a sum ofAl₂O₃+RE_(m)O_(n) less than or equal to 30.0 mol. %.

In some other embodiments, the glass composition may have a sum ofR₂O+RO less than or equal to 5.0 mol. % or less than or equal to 1.0mol. %.

In some embodiments, the glass composition may have a sum ofRE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO3 greater than or equal to 0.0 mol. %, greaterthan or equal to 10.0 mol. %, greater than or equal to 20.0 mol. %,greater than or equal to 30.0 mol. %, greater than or equal to 40.0 mol.%, greater than or equal to 50.0 mol. %, greater than or equal to 60.0mol. %, or greater than or equal to 65.0 mol. %. In some otherembodiments, the glass composition may have a sum ofRE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃ less than or equal to 69.0 mol. %, less thanor equal to 60.0 mol. %, less than or equal to 50.0 mol. %, less than orequal to 40.0 mol. %, less than or equal to 30.0 mol. %, less than orequal to 20.0 mol. %, or less than or equal to 10.0 mol. %. In some moreembodiments, the glass composition may have a sum ofRE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃ from 0.0 mol. % to 69.0 mol. %, from 0.0 mol.% to 50.0 mol. %, from 0.0 mol. % to 30.0 mol. %, from 10.0 mol. % to50.0 mol. %, from 10.0 mol. % to 30.0 mol. %, from 20.0 mol. % to 60.0mol. %, from 20.0 mol. % to 50.0 mol. %, from 30.0 mol. % to 69.0 mol.%, from 30.0 mol. % to 60.0 mol. %, from 40.0 mol. % to 60.0 mol. %,from 21.0 mol. % to 46.0 mol. %, from 33.0 mol. % to 63.0 mol. %, orfrom 9.0 mol. % to 39.0 mol. %.

In some other embodiments, the glass composition may have a sum ofSiO₂+GeO₂ less than or equal to 4.8 mol. %.

In some embodiments, the glass composition may have a sum of TiO₂+Nb₂O₅greater than or equal to 0.0 mol. %, greater than or equal to 0.6 mol.%, greater than or equal to 10.0 mol. %, greater than or equal to 20.0mol. %, greater than or equal to 21.0 mol. %, greater than or equal to30.0 mol. %, greater than or equal to 40.0 mol. %, or greater than orequal to 50.0 mol. %. In some other embodiments, the glass compositionmay have a sum of TiO₂+Nb₂O₅ less than or equal to 60.0 mol. %, lessthan or equal to 50.0 mol. %, less than or equal to 40.0 mol. %, lessthan or equal to 35.0 mol. %, less than or equal to 30.0 mol. %, lessthan or equal to 29.6 mol. %, less than or equal to 20.0 mol. %, or lessthan or equal to 10.0 mol. %. In some more embodiments, the glasscomposition may have a sum of TiO₂+Nb₂O₅ from 0.0 mol. % to 35.0 mol. %,from 0.6 mol. % to 60.0 mol. %, from 0.0 mol. % to 60.0 mol. %, from 0.0mol. % to 40.0 mol. %, from 10.0 mol. % to 40.0 mol. %, from 10.0 mol. %to 30.0 mol. %, from 10.0 mol. % to 20.0 mol. %, from 20.0 mol. % to40.0 mol. %, from 21.0 mol. % to 30.0 mol. %, from 8.0 mol. % to 35.0mol. %, from 3.0 mol. % to 43.0 mol. %, or from 15.0 mol. % to 55.0 mol.%.

In some embodiments, the glass composition may have a sum of WO3+TiO₂greater than or equal to 0.0 mol. %, greater than or equal to 5.0 mol.%, greater than or equal to 10.0 mol. %, greater than or equal to 15.0mol. %, greater than or equal to 20.0 mol. %, greater than or equal to23.0 mol. %, greater than or equal to 25.0 mol. %, greater than or equalto 30.0 mol. %, or greater than or equal to 35.0 mol. %. In some otherembodiments, the glass composition may have a sum of WO3+TiO₂ less thanor equal to 40.0 mol. %, less than or equal to 35.0 mol. %, less than orequal to 34.0 mol. %, less than or equal to 30.0 mol. %, less than orequal to 25.0 mol. %, less than or equal to 20.0 mol. %, less than orequal to 15.0 mol. %, less than or equal to 10.0 mol. %, or less than orequal to 5.0 mol. %. In some more embodiments, the glass composition mayhave a sum of WO3+TiO₂ from 0.0 mol. % to 40.0 mol. %, from 0.0 mol. %to 30.0 mol. %, from 0.0 mol. % to 15.0 mol. %, from 5.0 mol. % to 15.0mol. %, from 10.0 mol. % to 15.0 mol. %, from 20.0 mol. % to 40.0 mol.%, from 20.0 mol. % to 35.0 mol. %, from 20.0 mol. % to 30.0 mol. %,from 23.0 mol. % to 35.0 mol. %, from 23.0 mol. % to 34.0 mol. %, from8.0 mol. % to 20.0 mol. %, from 0 mol. % to 28.0 mol. %, or from 15.0mol. % to 27.0 mol. %.

In some embodiments, glass may have limitations for the differenceB₂O₃+SiO₂−P₂O₅. The difference (B₂O₃+SiO₂−P₂O₅) distinguishes borate,silicoborate and borosilicate glasses from phosphate glasses. Positivevalues of the difference (B₂O₃+SiO₂−P₂O₅) identify borate, silicoborateor borosilicate glasses, whereas negative values of this quantityidentify phosphate glasses. In some embodiments, the glass may have adifference B₂O₃+SiO₂−P₂O₅ greater than or equal to 0 mol. %. In someembodiments, the glass composition may have a difference B₂O₃+SiO₂−P₂O₅greater than or equal to 0 mol. %, greater than or equal to 1 mol. %,greater than or equal to 5 mol. %, greater than or equal to 10 mol. %,greater than or equal to 15 mol. %, greater than or equal to 20 mol. %,greater than or equal to 25 mol. %, greater than or equal to 30 mol. %,or greater than or equal to 35 mol. %. In some other embodiments, theglass composition may have a difference B₂O₃+SiO₂−P₂O₅ less than orequal to 40 mol. %, less than or equal to 35 mol. %, less than or equalto 30 mol. %, less than or equal to 25 mol. %, less than or equal to 20mol. %, or less than or equal to 15 mol. %. In some more embodiments,the glass composition may have a B₂O₃+SiO₂−P₂O₅ from 0 mol. % to 40 mol.%, from 0 mol. % to 10 mol. %, from 1 mol. % to 20 mol. %, from 1 mol. %to 10 mol. %, from 5 mol. % to 20 mol. %, from 5 mol. % to 10 mol. %,from 10 mol. % to 30 mol. %, from 10 mol. % to 20 mol. %, from 15 mol. %to 40 mol. %, from 15 mol. % to 35 mol. %, from 15 mol. % to 30 mol. %,from 15 mol. % to 25 mol. %, from 15 mol. % to 20 mol. %, from 20 mol. %to 25 mol. %, from 20 mol. % to 35 mol. %, from 6 mol. % to 25 mol. %,or from 9 mol. % to 31 mol. %.

In some embodiments, glass composition may have limitations for thedifference TiO₂−SiO₂. The higher this difference, the higher refractiveindex may be expected to reach at a given density. However, if thisdifference is too high, the risk of phase separation may appear, whichmay cause crystallization and/or loss of transmittance. In someembodiments, the glass may have a difference TiO₂−SiO₂ greater than orequal to 7.5 mol. %, greater than or equal to 8 mol. %, greater than orequal to 8 mol. %, greater than or equal to 10 mol. %, greater than orequal to 12 mol. %, or greater than or equal to 15 mol. %. In some otherembodiments, the glass composition may have a difference TiO₂−SiO₂ lessthan or equal to 16 mol. %, less than or equal to 15 mol. %, less thanor equal to 12 mol. %, or less than or equal to 10 mol. %. In some moreembodiments, the glass composition may have a TiO₂−SiO₂ from 8 mol. % to16 mol. %, from 8 mol. % to 15 mol. %, from 8 mol. % to 12 mol. %, from8 mol. % to 16 mol. %, from 8 mol. % to 15 mol. %, from 8 mol. % to 12mol. %, from 10 mol. % to 16 mol. %, from 10 mol. % to 15 mol. %, from10 mol. % to 12 mol. %, from 12 mol. % to 16 mol. %, from 12 mol. % to15 mol. %, from 9 mol. % to 12 mol. %, from 11 mol. % to 14 mol. %, orfrom 11 mol. % to 15 mol. %.

In some embodiments, the glass produced from the glass composition mayhave n_(d) from greater than or equal to 1.85 to less than or equal to2.10 and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass may have the n_(d) greater than or equal to 1.85,greater than or equal to 1.86, greater than or equal to 1.88, greaterthan or equal to 1.90, greater than or equal to 1.92, greater than orequal to 1.95, greater than or equal to 1.98, greater than or equal to2.01, greater than or equal to 2.04, greater than or equal to 2.05,greater than or equal to 2.06, or greater than or equal to 2.08. In someother embodiments, the glass may have the n_(d) less than or equal to2.10, less than or equal to 2.08, less than or equal to 2.08, less thanor equal to 2.07, less than or equal to 2.06, less than or equal to2.05, less than or equal to 2.04, less than or equal to 2.03, less thanor equal to 1.95, less than or equal to 1.92, less than or equal to1.90, less than or equal to 1.88, or less than or equal to 1.86.

In some more embodiments, the glass may have the n_(d) greater than orequal to 1.85 to 2.10, greater than or equal to 1.92 to 2.08, greaterthan or equal to 1.95 to 2.07, greater than or equal to 1.85 and lessthan or equal to 2.06, greater than or equal to 1.85 and less than orequal to 1.86, greater than or equal to 1.86 and less than or equal to1.95, greater than or equal to 1.88 and less than or equal to 2.07,greater than or equal to 1.88 and less than or equal to 1.92, greaterthan or equal to 1.90 and less than or equal to 2.07, greater than orequal to 1.90 and less than or equal to 1.92, greater than or equal to1.92 and less than or equal to 2.04, greater than or equal to 1.95 andless than or equal to 2.08, greater than or equal to 1.95 and less thanor equal to 2.06, greater than or equal to 1.95 and less than or equalto 2.04, greater than or equal to 2.03 and less than or equal to 2.08,greater than or equal to 2.03 and less than or equal to 2.06, greaterthan or equal to 1.86 and less than or equal to 1.94, greater than orequal to 1.87 and less than or equal to 1.98, or greater than or equalto 1.98 and less than or equal to 2.08.

In some embodiments, the glass composition may have a liquidustemperature T_(liq) from greater than or equal to 850° C. to less thanor equal to 1350° C. and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition may have the T_(liq)greater than or equal to 850° C., greater than or equal to 860° C.,greater than or equal to 880° C., greater than or equal to 900° C.,greater than or equal to 1000° C., greater than or equal to 1065° C.,greater than or equal to 1100° C., greater than or equal to 1200° C.,greater than or equal to 1300° C., greater than or equal to 1320° C., orgreater than or equal to 1340° C. In some other embodiments, the glasscomposition may have the T_(liq) less than or equal to 1350° C., lessthan or equal to 1340° C., less than or equal to 1320° C., less than orequal to 1300° C., less than or equal to 1200° C., less than or equal to1108° C., less than or equal to 1100° C., less than or equal to 1050°C., less than or equal to 1000° C., less than or equal to 900° C., lessthan or equal to 880° C., or less than or equal to 860° C. In some moreembodiments, the glass composition may have the T_(liq) greater than orequal to 850° C. to 1350° C., greater than or equal to 850° C. and lessthan or equal to 1200° C., greater than or equal to 850° C. and lessthan or equal to 1000° C., greater than or equal to 860° C. and lessthan or equal to 1300° C., greater than or equal to 860° C. and lessthan or equal to 900° C., greater than or equal to 880° C. and less thanor equal to 1350° C., greater than or equal to 880° C. and less than orequal to 1300° C., greater than or equal to 880° C. and less than orequal to 1100° C., greater than or equal to 880° C. and less than orequal to 900° C., greater than or equal to 900° C. and less than orequal to 1300° C., greater than or equal to 1000° C. and less than orequal to 1200° C., greater than or equal to 1000° C. and less than orequal to 1100° C., greater than or equal to 1050° C. and less than orequal to 1350° C., greater than or equal to 1050° C. and less than orequal to 1100° C., greater than or equal to 1100° C. and less than orequal to 1320° C., greater than or equal to 919° C. and less than orequal to 1175° C., greater than or equal to 1100° C. and less than orequal to 1308° C., or greater than or equal to 919° C. and less than orequal to 1100° C.

In some embodiments, the glass may have a glass transition temperatureT_(g) from greater than or equal to 500° C. to less than or equal to725° C. and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass may have the T_(g) greater than or equal to500° C., greater than or equal to 510° C., greater than or equal to 520°C., greater than or equal to 530° C., greater than or equal to 550° C.,greater than or equal to 600° C., greater than or equal to 625° C.,greater than or equal to 650° C., greater than or equal to 660° C.,greater than or equal to 700° C., greater than or equal to 710° C., orgreater than or equal to 720° C. In some other embodiments, the glassmay have the T_(g) less than or equal to 725° C., less than or equal to720° C., less than or equal to 710° C., less than or equal to 700° C.,less than or equal to 687° C., less than or equal to 650° C., less thanor equal to 600° C., less than or equal to 550° C., less than or equalto 530° C., less than or equal to 520° C., or less than or equal to 510°C. In some more embodiments, the glass may have the T_(g) greater thanor equal to 500° C. to 700° C., greater than or equal to 500° C. andless than or equal to 725° C., greater than or equal to 500° C. and lessthan or equal to 600° C., greater than or equal to 500° C. and less thanor equal to 520° C., greater than or equal to 510° C. and less than orequal to 700° C., greater than or equal to 510° C. and less than orequal to 600° C., greater than or equal to 520° C. and less than orequal to 725° C., greater than or equal to 520° C. and less than orequal to 700° C., greater than or equal to 530° C. and less than orequal to 710° C., greater than or equal to 530° C. and less than orequal to 600° C., greater than or equal to 550° C. and less than orequal to 710° C., greater than or equal to 550° C. and less than orequal to 600° C., greater than or equal to 600° C. and less than orequal to 710° C., greater than or equal to 600° C. and less than orequal to 687° C., greater than or equal to 650° C. and less than orequal to 725° C., greater than or equal to 650° C. and less than orequal to 720° C., greater than or equal to 650° C. and less than orequal to 687° C., greater than or equal to 597° C. and less than orequal to 718° C., greater than or equal to 531° C. and less than orequal to 670° C., or greater than or equal to 531° C. and less than orequal to 630° C.

In some embodiments, the glass may have the density at room temperatured_(RT) from greater than or equal to 4.50 g/cm³ to less than or equal to6.00 g/cm³ and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass may have the d_(RT) greater than or equalto 4.50 g/cm³, greater than or equal to 4.60 g/cm³, greater than orequal to 4.70 g/cm³, greater than or equal to 4.80 g/cm³, greater thanor equal to 5.00 g/cm³, greater than or equal to 5.50 g/cm³, greaterthan or equal to 5.70 g/cm³, greater than or equal to 5.80 g/cm³, orgreater than or equal to 5.90 g/cm³. In some other embodiments, theglass may have the d_(RT) less than or equal to 6.00 g/cm³, less than orequal to 5.90 g/cm³, less than or equal to 5.80 g/cm³, less than orequal to 5.70 g/cm³, less than or equal to 5.50 g/cm³, less than orequal to 5.30 g/cm³, less than or equal to 5.00 g/cm³, less than orequal to 4.80 g/cm³, less than or equal to 4.70 g/cm³, or less than orequal to 4.60 g/cm³. In some more embodiments, the glass may have thed_(RT) greater than or equal to 4.50 g/cm³ to 5.50 g/cm³, greater thanor equal to 4.50 g/cm³ and less than or equal to 6.00 g/cm³, greaterthan or equal to 4.50 g/cm³ and less than or equal to 5.70 g/cm³,greater than or equal to 4.60 g/cm³ and less than or equal to 5.70g/cm³, greater than or equal to 4.70 g/cm³ and less than or equal to5.50 g/cm³, greater than or equal to 4.70 g/cm³ and less than or equalto 5.00 g/cm³, greater than or equal to 4.80 g/cm³ and less than orequal to 5.80 g/cm³, greater than or equal to 4.80 g/cm³ and less thanor equal to 5.50 g/cm³, greater than or equal to 4.80 g/cm³ and lessthan or equal to 5.00 g/cm³, greater than or equal to 5.00 g/cm³ andless than or equal to 5.80 g/cm³, greater than or equal to 5.30 g/cm³and less than or equal to 5.90 g/cm³, greater than or equal to 5.30g/cm³ and less than or equal to 5.70 g/cm³, greater than or equal to5.30 g/cm³ and less than or equal to 5.50 g/cm³, greater than or equalto 4.73 g/cm³ and less than or equal to 5.42 g/cm³, greater than orequal to 5.05 g/cm³ and less than or equal to 5.50 g/cm³, or greaterthan or equal to 5.14 g/cm³ and less than or equal to 5.70 g/cm³.

In some embodiments, the glass composition may have the decimallogarithm of liquidus viscosity greater than or equal to 0.5 or greaterthan or equal to 0.75.

In some embodiments, the glass may have a quantityn_(d)−(1.437+0.0005*T_(liq)) greater than or equal to 0.

In some embodiments, the glass may have a quantityn_(d)−(1.481+0.0005*T_(liq)) greater than or equal to 0.

In some embodiments, the glass may have a quantity(n_(d)−1)/d_(RT)−(0.269−0.12*T_(i)) greater than or equal to 0.

In some embodiments, the glass may have a quantity(n_(d)−1)/d_(RT)−(0.274−0.12*T_(i)) greater than or equal to 0.

In some embodiments, the glass may have a quantityn_(d)−(1.571+0.083*d_(RT)) greater than or equal to 0.

Transmittance index T_(i) is a quantity calculated by the followingformula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅),  (I)

where chemical formulas mean the amounts of corresponding components inthe glass composition expressed in mol. %.

FIG. 1 shows the relationship between the transmittance index T_(i)according to formula (I) and the quantity λ_(70%). The quantity λ_(70%)is a measured quantity and indicates the minimum wavelengthcorresponding to a total transmittance of 70% or higher for a glasssample in the form of a plate having a thickness of 10 mm. Lower valuesof λ_(70%) generally correspond to a higher range of wavelengths atwhich the glass sample has a high internal transmittance, and thereforelower values of λ_(70%) generally correspond to a higher transmittanceof the glass sample overall. The data points in FIG. 1 correspond todata taken from U.S. Pat. No. 10,287,205 (labeled as U.S. Ser. No.10/287,205), U.S. Patent Application No. 2011/105294 (labeled as US2011105294) and WO Patent Application No. 2020/034215 (labeled as WO2020034215). U.S. Pat. No. 10,287,205 reported glass compositions interms of cation percent. To calculate the transmittance index T_(i)according to formula (I) in mol. %, the cation percent values wereassumed to be equivalent to atomic percent of atoms, excluding oxygen,and the cation percent values were converted to mole percent of oxidesand applied to formula (I). As illustrated in FIG. 1, the datademonstrate a correlation between the quantity λ_(70%) and thetransmittance index T_(i).

Refractive index n_(d), density d_(RT), refraction (n_(d)−1)/d_(RT) andglass transition temperature T_(g) are properties of glass that can bepredicted from the glass composition. A linear regression analysis ofthe Exemplary Glasses of the present disclosure in the EXAMPLES sectionbelow and other glass compositions reported in the literature wasperformed to determine equations that can predict the compositiondependences of the refractive index n_(d), density d_(RT), refraction(n_(d)−1)/d_(RT) and glass transition temperature T_(g).

The training dataset of glass compositions satisfying the criteriaspecified in Table 1 below and having measured values of the propertiesof interest, about 100 glass compositions for each property (refractiveindex n_(d), density d_(RT), refraction (n_(d)−1)/d_(RT) and glasstransition temperature T_(g)), was randomly selected from the literaturedata presented in the publicly available SciGlass Information Systemdatabase and from the Exemplary Glasses from the embodiments presentedherein. The linear regression analysis on the above-specified datasetwas used to determine the formulas, with the exclusion of insignificantvariables and outliers. The resulting formulas are presented in Table 2below. Another part of glass compositions satisfying the same criteriawas used as a validation set to evaluate the ability to interpolatewithin predefined compositional limits, which corresponds to thestandard deviations specified in the Table 2. An external dataset ofprior art glass compositions, also randomly selected from the SciGlassInformation System database, was used to evaluate the ability to predictthe properties outside of the specified compositional limits with areasonable accuracy. Multiple iterations of this process were performedin order to determine the best variant for each property, correspondingto the above-mentioned regression formulas specified in the Table 2.

The data for the Comparative Glass compositions used in the linearregression modeling, including the training dataset, validation datasetand external dataset were obtained from the publically availableSciGlass Information System database. Formulas (II), (III), (IV) and (V)below were obtained from the linear regression analysis and used topredict the refractive index n_(d), density d_(RT), refraction(n_(d)-1)/d_(RT) and glass transition temperature T_(g), respectively,of the glasses:

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)

P_(ref)(cm³/g)=0.000087034*SiO₂−0.00012035*B₂O₃−0.0012566*La₂O₃+0.0011411*TiO₂−0.00031654*ZnO+0.000088066*CaO+0.0020444*Nb₂O₅−0.00023383*MgO−0.00086501*BaO−0.0004486*WO₃−0.0014114*Gd₂O₃−0.00023872*Y₂O₃−0.00031575*Ta₂O₅+0.00011894*Li₂O+0.00027178*Al₂O₃−0.000099802*Na₂O−0.00028391*GeO₂−0.00030531*SrO−0.00072061*Bi₂O₃−0.0010964*Yb₂O₃+0.00022839*K₂O−0.00086617*PbO+0.00027129*TeO₂+0.198,  (IV)

P _(Tg)(°C.)=595.358−0.63217*B₂O₃−0.46552*SiO₂+1.1849*TiO₂+0.59610*Nb₂O₅−1.6293*WO₃+1.3877*ZrO₂+4.4090*La₂O₃+4.1695*Y₂O₃−5.0756*Bi₂O₃+0.55630*CaO−5.3892*PbO−4.2774*TeO₂+1.8497*Al₂O₃−0.40659*GeO₂−1.7011*ZnO−4.1520*Li₂O+3.0777*Gd₂O₃.  (V)

In Formulas (II), (III), (IV) and (V) and Tables 1 and 2, refractiveindex parameter P_(n) is a parameter that predicts the refractive indexn_(d) at 587.56 nm, calculated from the components of the glasscomposition expressed in mol. %; density parameter P_(d) is a parameterthat predicts the density d_(RT) at room temperature [g/cm³], calculatedfrom the components of the glass composition expressed in mol. %;refraction parameter P_(ref) is a parameter that predicts the refraction(n_(d)−1)/d_(RT), calculated from the components of the glasscomposition expressed in mol. %; and T_(g) parameter P_(Tg) is aparameter that predicts the glass transition temperature T_(g) [° C.],calculated from the components of the glass composition expressed inmol. %.

In Formulas (II), (III), (IV) and (V), each component of the glasscomposition is listed in terms of its chemical formula, where thechemical formula refers to the concentration of the component in theas-batched glass composition expressed in mol. %. It is understood thatnot all components listed in Formulas (II), (III), (IV) and (V) arenecessarily present in a particular glass composition and that Formulas(II), (III), (IV) and (V) are equally valid for glass compositions thatcontain less than all of the components listed in the formulas. It isfurther understood that Formulas (II), (III), (IV) and (V) are alsovalid for glass compositions within the scope and claims of the presentdisclosure that contain components in addition to the components listedin the formulas. If a component listed in Formulas (II), (III), (IV) and(V) is absent in a particular glass composition, the concentration ofthe component in the glass composition is 0 mol. % and the contributionof the component to the value calculated from the formulas is zero.

In Table 1, RE_(m)O_(n) is a total sum of rare earth metal oxides.

TABLE 1 Composition Space Used for Modeling Property n_(d) d_(RT), g/cm³(n_(d) − 1)/d_(RT) T_(g), ° C. Min, Max, Min, Max, Min, Max, Min, Max,Component limits mol. % mol. % mol. % mol. % mol. % mol. % mol. % mol. %TiO₂ 5 40 1 20 0 20 1 35 La₂O₃ 0 30 1 30 0 30 Not Not limited limitedB₂O₃ 5 30 0 35 0 35 5 30 SiO₂ 0 15 0 30 0 30 0 15 ZrO₂ 0 10 0 20 0 20 015 Nb₂O₅ 0 15 0 15 0 15 0 15 CaO 0 20 Not Not Not Not 0 20 limitedlimited limited limited BaO 0 10 Not Not Not Not 0 10 limited limitedlimited limited WO₃ 0 30 1 25 0 25 0 30 Bi₂O₃ 0 20 Not Not Not Not 0 20limited limited limited limited PbO 0 15 Not Not Not Not 0 15 limitedlimited limited limited P₂O₅ 0 10 0 10 0 10 0 10 TeO₂ 0 20 Not Not 0 100 20 limited limited Al₂O₃ + RE_(m)O_(n) 0 30 Not Not Not Not 0 30limited limited limited limited GeO₂ 0 10 Not Not Not Not 0 10 limitedlimited limited limited F 0 3 [at. %] 0 5 [at. %] 0 5 [at. %] Not Notlimited limited La₂O₃ + Gd₂O₃ + Not Not 10 Not 10 Not Not Not ZrO₂ +TiO₂ + Nb₂O₅+ limited limited limited limited limited limited WO₃ +Bi₂O₃ La₂O₃ + Gd₂O₃ Not Not Not Not Not Not 1 35 limited limited limitedlimited limited limited F + Cl + Br + I Not Not Not Not Not Not 0 3limited limited limited limited limited limited TiO₂ + Nb₂O₅ Not Not NotNot Not Not Not 45 limited limited limited limited limited limitedlimited SiO₂ + B₂O₃ − P₂O₅ Not Not Not Not Not Not 0 Not limited limitedlimited limited limited limited limited Li₂O + Na₂O + K₂O Not Not NotNot Not Not 0 25 limited limited limited limited limited limited Otherspecies 0 Not 0 Not 0 Not 0 Not limited limited limited limited

TABLE 2 Property prediction models Predicting Regression CompositionStandard Property Abbreviation Unit Parameter Formula Unit errorRefractive index at n_(d) P_(n) Formula (II) Mol. % 0.021 587.56 nmDensity at room d_(RT) g/cm³ P_(d) Formula (III) Mol. % 0.12 temperatureRefractive index to (n_(d) − cm³/g P_(ref) Formula (IV) Mol. % 0.006density ratio 1)/d_(RT) (“refraction”) Glass transition T_(g) ° C.P_(Tg) Formula (V) Mol. % 15 temperature

FIG. 2 is a plot of the parameter P_(n) calculated by Formula (II) as afunction of measured refractive index n_(d) for some Literature Glasses(“Comp. Glasses”) and some Exemplary Glasses (“Ex. Glasses”). Asillustrated by the data in FIG. 2, the compositional dependence of theparameter P_(n) had an error within a range of ±0.021 unit of themeasured n_(d) for the majority of glasses, that corresponds to thestandard error specified in Table 2.

FIG. 3 is a plot of the parameter P_(d) calculated by Formula (III) as afunction of measured density d_(RT) for some Literature Glasses (“Comp.Glasses”) and some Exemplary Glasses (“Ex. Glasses”). As illustrated bythe data in FIG. 3, the compositional dependence of the parameter P_(d)had an error within a range of ±0.12 unit of the measured d_(RT) for themajority of glasses, that corresponds to the standard error specified inTable 2.

FIG. 4 is a plot of the parameter P_(ref) calculated by Formula (IV) asa function of measured refraction (n_(d)−1)/d_(RT) for some LiteratureGlasses (“Comp. Glasses”) and some Exemplary Glasses (“Ex. Glasses”). Asillustrated by the data in FIG. 4, the compositional dependence of theparameter P_(ref) had an error within a range of ±0.006 unit of themeasured (n_(d)−1)/d_(RT) for the majority of glasses, that correspondsto the standard error specified in Table 2.

FIG. 5 is a plot of the parameter P_(Tg) calculated by Formula (V) as afunction of measured glass transition temperature T_(g) for someLiterature Glasses (“Comp. Glasses”) and some Exemplary Glasses (“Ex.Glasses”). As illustrated by the data in FIG. 5, the compositionaldependence of the parameter P_(Tg) had an error within a range of ±15unit of the measured T_(g) for the majority of glasses, that correspondsto the standard error specified in Table 2.

When considering T_(g) as a function of glass composition, one shouldunderstand that the numerical value of this quantity may depend on themethod of its measurement (such as differential scanning calorimetry[DSC], differential thermal analysis [DTA], thermomechanical analysis[TMA] and others), measurement conditions (such as heating rate whenmeasuring T_(g) when heating a sample), and the thermal history, thatmeans the time-temperature schedule of preliminary thermal treatment,starting from melting a sample. That is why comparison of measuredvalues of T_(g) with the results of calculation from the glasscomposition may give some deviations caused by different method ofmeasurement, and/or different process conditions, and/or differentthermal history. The analysis of published data taken from differentsources, performed with the use of the publicly available SciGlassInformation System database shows that typically the values of T_(g)reported for same compositions and obtained in different ways deviatefrom each other within approximately ±10-20° C., which is, typically,many times less than the variation of T_(g) caused by changing the glasscompositions within the ranges considered in the present disclosure.

Accordingly, the formula for prediction of T_(g) from the glasscomposition presented in the present disclosure relates to theexperimental conditions and methods described in the disclosure, whichassumes the measurement by DSC method when heating the glass sampleswith the rate of 10° C./min cooled according to the procedure describedin the present disclosure without special preliminary treatment. Whencomparing the results of such calculations with the data published inthe literature, it is assumed that the published values of T_(g)typically do not deviate from the values obtained in the conditions usedherein by more than approximately 20° C.

Table 3 identifies the combination of components and their respectiveamounts according to some embodiments of the present disclosure. TheExemplary Glasses A in Table 3 may include additional componentsaccording to any aspects of the present disclosure as described herein.

TABLE 3 Exemplary Glasses A Composition Amount (mol. %) WO₃ 3.0 to 35.0mol. % TiO₂ 0.3 to 50.0 mol. % Nb₂O₅ 0.3 to 50.0 mol. % Bi₂O₃ 0.0 to20.0 mol. % TeO₂ 0.0 to 10.0 mol. % PbO 0.0 to 5.0 mol. % F 0.0 to 5.0at. % Sum of (TiO₂ + Nb₂O₅) 0.6 to 60.0 mol. %

Exemplary Glasses A according to embodiments of the present disclosuremay have a refractive index at 587.56 nm n_(d) from 1.92 to 2.08.

According to some embodiments of the present disclosure, ExemplaryGlasses A may also have a liquidus temperature T_(liq) [° C.] from 850to 1350.

According to some embodiments of the present disclosure, ExemplaryGlasses A may also satisfy the following formula:

n _(d)−(1.437+0.0005*T _(liq))>0.00,

where n_(d) is a refractive index at 587.56 nm, and T_(liq) is aliquidus temperature.

According to some embodiments of the present disclosure, ExemplaryGlasses A may also satisfy the following formula:

n _(d)−(1.481+0.0005*T _(liq))>0.00,

where n_(d) is a refractive index at 587.56 nm, and T_(liq) is aliquidus temperature.

Table 4 identifies the combination of components and their respectiveamounts according to some embodiments of the present disclosure. TheExemplary Glasses B in Table 4 may include additional componentsaccording to any aspects of the present disclosure as described herein.

TABLE 4 Exemplary Glasses B Composition Amount (mol. %) TiO₂ 7.5 to 28.0mol. % B₂O₃ 1.0 to 40.0 mol. % Nb₂O₅ 0.3 to 19.5 mol. % WO₃ 0.0 to 35.0mol. % La₂O₃ 0.0 to 25.0 mol. % Gd₂O₃ 0.0 to 25.0 mol. % Bi₂O₃ 0.0 to20.0 mol. % ZrO₂ 0.0 to 20.0 mol. % TeO₂ 0.0 to 20.0 mol. % SiO₂ 0.0 to13.5 mol. % Al₂O₃ 0.0 to 10.0 mol. % ThO₂ 0.0 to 10.0 mol. % GeO₂ 0.0 to10.0 mol. % Ta₂O₅ 0.0 to 10.0 mol. % PbO 0.0 to 5.0 mol. % F 0.0 to 5.0at. % Sum of (WO₃ + TiO₂) ≤40.0 mol. % Sum of (TiO₂ + Nb₂O₅) ≤35.0 mol.% Sum of (R₂O + RO) 0.0 to 5.0 mol. % Sum of (RE₂O₃ + ZrO₂ + TiO₂ +Nb₂O₅ + WO₃) ≥10.0 mol. %

Exemplary Glasses B according to embodiments of the present disclosuremay satisfy the following condition:

TiO₂−SiO₂[mol. %]≥7.5,

where chemical formulas refer to the amounts of components in glass,expressed in mol. %.

According to some embodiments of the present disclosure, ExemplaryGlasses B may also satisfy the following condition:

B₂O₃+SiO₂−P₂O₅[mol. %]≥0.00,

where chemical formulas refer to the amounts of components in glass,expressed in mol. %.

According to some embodiments of the present disclosure, ExemplaryGlasses B may also have a refractive index at 587.56 nm n_(d) from 1.85to 2.1.

According to some embodiments of the present disclosure, ExemplaryGlasses B may also satisfy the following formula:

(n _(d)−1)/d _(RT)−(0.269−0.12*T _(i))>0.00,

where (n_(d)−1)/d_(RT) is a refractive index to density ratio(“refraction”) (cm³/g), and T_(i) is a transmittance index.

According to some embodiments of the present disclosure, ExemplaryGlasses B may also satisfy the following formula:

(n _(d)−1)/d _(RT)−(0.274−0.12*T _(i))>0.00,

where (n_(d)−1)/d_(RT) is a refractive index to density ratio(“refraction”) (cm³/g), and T_(i) is a transmittance index.

Table 5 identifies the combination of components and their respectiveamounts according to some embodiments of the present disclosure. TheExemplary Glasses C in Table 5 may include additional componentsaccording to any aspects of the present disclosure as described herein.

TABLE 5 Exemplary Glasses C Composition Amount (mol. %) WO₃ 1.0 to 40.0mol. % ZrO₂ 0.3 to 20.0 mol. % B₂O₃ 0.0 to 40.0 mol. % La₂O₃ 0.0 to 35.0mol. % Bi₂O₃ 0.0 to 35.0 mol. % ZnO 0.0 to 35.0 mol. % Ta₂O₅ 0.0 to 25.0mol. % Al₂O₃ 0.0 to 10.0 mol. % ThO₂ 0.0 to 10.0 mol. % TeO₂ 0.0 to 10.0mol. % V₂O₅ 0.0 to 5.0 mol. % Sum of (TiO₂ + Nb₂O₅) 0.0 to 35.0 mol. %Sum of (RE₂O₃ + ZrO2 + TiO2 + Nb2O5 + WO3) ≥10.0 mol. %

Exemplary Glasses C according to embodiments of the present disclosuremay satisfy the following condition:

B₂O₃+SiO₂−P₂O₅[mol. %]≥0.50,

where chemical formulas refer to the amounts of components in glass,expressed in mol. %.

According to some embodiments of the present disclosure, ExemplaryGlasses C may also have a glass transition temperature T_(g) [° C.] from500 to 700.

According to some embodiments of the present disclosure, ExemplaryGlasses C may also have a density at room temperature d_(RT) [g/cm³] ofless than or equal to 6.

According to some embodiments of the present disclosure, ExemplaryGlasses C may also satisfy the following formula:

n _(d)−(1.571+0.083*d _(RT))>0.00,

where n_(d) is a refractive index at 587.56 nm, and d_(RT) is a densityat room temperature (g/cm³).

EXAMPLES

The following examples describe various features and advantages providedby the disclosure, and are in no way intended to limit the invention andappended claims.

To prepare the glass samples for some exemplary glasses of the presentdisclosure, about 15 grams of each sample (content of intendedcomponents in the as-batched composition was more than 99.99 wt %) wasmelted from batch raw materials at a temperature of about 1300° C. inplatinum or platinum-rhodium crucibles (Pt:Rh=80:20) for 1 hour. Twocontrolled cooling conditions were applied. In the first condition(referred to as “15 min test” or “15 min devit test”), it took about 15min for the samples to cool from 1100° C. to 500° C. inside a furnace.In the second condition (referred to as “2.5 min test” or “2.5 min devittest”), it took about 2.5 min for the samples to cool from 1100° C. to500° C. in air inside a furnace. Temperature readings were obtained bydirect reading of the furnace temperature or using an IR camera readingwith calibration scaling. The first condition (15 min test)approximately corresponds to the cooling rate of up to 300° C./min at atemperature of 1000° C. and the second test approximately corresponds tothe cooling rate of up to 600° C./min at 1000° C. (near to thistemperature, the cooling rate approached the maximum). When thetemperature is lower, the cooling rate also decreases significantly.Typical schedules of the first and second cooling regimes are shown inFIG. 6. For these samples, observations referred to as “15-min devittest” and “2.5-min devit test”, are specified in Table 6 below; theobservation “1” is used to denote that a glass composition passed theindicated devit test, where a composition is deemed to have passed theindicated devit test if a melt of the composition forms a glass free ofcrystals visible under an optical microscope under magnification from100× to 500×. The observation “0” is used to denote that a glasscomposition failed the indicated devit test.

To prepare other glass samples for exemplary glasses of the presentdisclosure, unless otherwise specified, a one kilogram batch of thecomponents was prepared in a pure platinum crucible. The crucible wasplaced in a furnace set at a temperature of 1250° C., after which, thetemperature in the furnace was raised to 1300° C. and held at 1300° C.for 2 hours. The furnace temperature was then reduced to 1250° C. andthe glass was allowed to equilibrate at this temperature for an hourbefore being poured on a steel table followed by annealing at Tg for anhour.

Some sample melts were also melted in a “one liter” platinum crucibleheated by Joule effect. In this process, approximately 3700 g of rawmaterials was used. The crucible was filled in 1.5 hours at 1250° C. Thetemperature was then raised to 1300° C. and held for one hour. Duringthis step, the glass was continuously stirred at 60 rpm. The temperaturewas then decreased to 1200° C. where it was allowed to equilibrate for30 minutes and the stirring speed was decreased to 20 rpm. The deliverytube was heated at 1225° C. and the glass was cast on a cooled graphitetable. The glass was formed into a bar of approximately 25 mm inthickness, 50 mm in width, and 90 cm in length. The prepared bars wereinspected under an optical microscope to check for crystallization andwere all crystal free. The glass quality observed under the opticalmicroscope was good with the bars being free of striae and bubbles. Theglass was placed at Tg in a lehr oven for 1 hour for a rough annealing.The bars were then annealed in a static furnace for one hour at Tg andthe temperature was then lowered at 1° C./min.

Some of samples were bleached after melting to improve thetransmittance. Bleaching process was performed at the temperaturesbetween 500° C. and the crystallization onset temperature T_(x). Whenthe temperature is less than about 500° C., the bleaching process maytake too long time because of its slow rate. When the temperature ofbleaching exceeds T_(x), the glass may crystallize when heat-treating.The higher the bleaching temperature, the faster the bleaching processgoes, but the lower value of resulting transmittance can be obtained.

No chemical analysis of the tested samples was performed becausechemical analysis was performed for similar samples prepared inindependent meltings by XRF method (X-ray fluorescence—for all oxides,except for B₂O₃ and Li₂O), by ICP method (inductively coupled plasmamass spectrometry—for B₂O₃) and by FES method (flame emissionspectrometry—for Li₂O). These analyses gave deviations from theas-batched compositions within ±2.0 mass % for the major components suchas Nb₂O₅ which is equivalently less than about 1 mol %. In Tables 6 and7, the abbreviation “n” with a subscript refers to the refractive indexat a corresponding wavelength in nm; for example, n_(632.8nm) refers tothe refractive index at wavelengths of 632.8 nm. T_(x) refers to thecrystallization onset temperature.

For some of Exemplary Glasses, including the Exemplary Glass 1, theliquidus temperature was measured by using several of theabove-specified methods, including the gradient boat test withobservation of the resulting material by a naked eye, and isothermaltests for 24 hours with observation of the resulting material under anoptical microscope. Both methods provided the results that wereconsistent with each other within ±7° C.

TABLE 6 Exemplary Glass Compositions Exemplary Glass 1 2 3 4 5 6 7 8Composition - mol. % B₂O₃ mol. % 32.98 32.98 32.98 33.87 27.96 28.4828.93 29.35 WO₃ mol. % 15.99 15.99 15.99 12.11 6.99 5.05 3.56 2.05 La₂O₃mol. % 19.99 19.99 19.99 20.00 24.96 24.94 24.94 24.94 TiO₂ mol. % 8.998.99 8.99 9.29 16.97 16.97 16.95 16.95 Nb₂O₅ mol. % 15.00 15.00 15.0016.45 8.48 9.17 9.70 10.25 SiO₂ mol. % 0.0301 0.0301 0.0301 1.27 7.488.03 8.45 8.89 ZrO₂ mol. % 7.00 7.00 7.00 7.00 6.99 7.12 7.22 7.33 CeO₂mol. % 0 0 0 0 0.15 0.15 0.15 0.15 CaO mol. % 0 0 0 0 0.0297 0.05870.0583 0.0578 Na₂O mol. % 0 0 0 0 0 0.0266 0.0264 0.0261 Ta₂O₅ mol. %0.0123 0.0123 0.0123 0.0161 0.0075 0.0075 0.0074 0.011 Compositionconstraints TiO₂ + Nb₂O₅ mol. % 23.99 23.99 23.99 25.74 25.47 26.1526.67 27.21 RE₂O₃ + ZrO₂ + mol. % 66.98 66.98 66.98 64.84 64.50 63.3762.50 61.63 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 24.98 24.98 24.98 21.3923.97 22.03 20.52 19.01 R₂O + RO mol. % 0 0 0 0 0.02971 0.08536 0.084670.08394 TiO₂ − SiO₂ mol. % 8.963 8.963 8.963 8.015 9.492 8.943 8.5038.059 B₂O₃ + SiO₂ − mol. % 33.01 33.01 33.01 35.14 35.46 36.53 37.4138.27 P₂O₅ SiO₂ + GeO₂ mol. % 0.03011 0.03011 0.03011 1.270 7.487 8.0368.460 8.900 Measured properties n_(d) 2.0051 1.9942 d_(RT) g/cm³ 5.0855.090 5.010 4.961 4.918 (n_(d) − 1)/d_(RT) cm³/g 0.19766 0.19533 15 −min devit test 1 1 1 1 (0/1) T_(liq) ° C. 1027.0 T_(g) ° C. 638.90642.30 644.00 644.00 Log(η_(liq)) P 0.80620 λ_(70%) nm 439 n_(d) −(1.437 + 0.0005 * 0.0546 T_(liq)) n_(d) − (1.481 + 0.0005 * 0.0106T_(liq)) (n_(d) − 1)/d_(RT) − 0.0057 −0.0011 (0.269 − 0.12 * T_(i))(n_(d) − 1)/d_(RT) − 6.800E−04 −0.0061 (0.274 − 0.12 * T_(i)) n_(d) −(1.571 + 0.083 * d_(RT)) 0.0121 7.700E−04 Predicted and calculatedproperties T_(i) 0.6418 0.6418 0.6418 0.603 0.6047 0.5868 0.5727 0.5579P_(n) [for n_(d)] 2.035 2.035 2.035 2.0312 2.0079 2.0053 2.0032 2.0012P_(ref) [for (n_(d) − 1)/d_(RT)] cm³/g 0.2027 0.2027 0.2027 0.20770.1975 0.1998 0.2015 0.2033 P_(Tg) [for T_(g)] ° C. 665.9 665.9 665.9672.3 707.8 710.9 713.3 715.8 P_(d) [for d_(RT)] g/cm³ 5.2082 5.20825.2082 5.0652 5.1082 5.038 4.9839 4.9291 P_(ref) − (0.269 − 0.12 *T_(i)) 0.0107 0.0107 0.0107 0.0111 0.0011 0.0012 0.0012 0.0012 P_(ref) −(0.274 − 0.12 * T_(i)) 0.0057 0.0057 0.0057 0.0061 −0.0039 −0.0038−0.0038 −0.0038 P_(n) − (1.571 + 0.083 * P_(d)) 0.0317 0.0317 0.03170.0398 0.0129 0.0161 0.0185 0.0211 Exemplary Glass 9 10 11 12 13 14 1516 Composition - mol. % B₂O₃ mol. % 27.96 28.52 27.95 27.97 28.43 27.9628.45 28.86 WO₃ mol. % 6.99 5.03 7.09 10.07 6.86 13.97 10.46 7.57 La₂O₃mol. % 24.96 21.61 21.45 20.81 23.14 19.98 22.49 24.53 TiO₂ mol. % 16.9716.97 19.91 18.20 18.14 15.97 15.98 15.97 Nb₂O₅ mol. % 8.48 9.19 8.748.85 8.85 8.98 8.98 8.98 SiO₂ mol. % 7.48 8.60 7.47 6.82 7.15 6.00 6.366.69 Bi₂O₃ mol. % 0 2.80 0 0 0 0 0 0 ZrO₂ mol. % 6.99 7.12 7.23 7.137.25 6.99 7.11 7.22 CeO₂ mol. % 0.15 0.13 0.13 0.12 0.14 0.12 0.14 0.15CaO mol. % 0.0297 0.0298 0.0283 0.0289 0.029 0.0296 0.0298 0.0299 Ta₂O₅mol. % 0.0075 0.0076 0.0072 0.0073 0.0074 0.0075 0.0076 0.0076Composition constraints TiO₂ + Nb₂O₅ mol. % 25.47 26.18 28.67 27.0627.01 24.96 24.98 24.97 RE₂O₃ + ZrO₂ + mol. % 64.50 60.01 64.52 65.1664.36 65.99 65.13 64.39 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 23.97 22.0127.02 28.29 25.02 29.96 26.45 23.56 R₂O + RO mol. % 0.02971 0.029830.02830 0.02888 0.02903 0.02963 0.02977 0.02988 TiO₂ − SiO₂ mol. % 9.4928.380 12.45 11.39 11.00 9.97 9.627 9.291 B₂O₃ + SiO₂ − mol. % 35.4637.15 35.44 34.80 35.60 33.97 34.83 35.57 P₂O₅ SiO₂ + GeO₂ mol. % 7.4878.602 7.474 6.819 7.152 6.001 6.364 6.693 Measured properties n_(d)2.003 d_(RT) g/cm³ 4.958 5.033 5.037 5.102 5.099 5.101 (n_(d) −1)/d_(RT) cm³/g 0.19658 15 − min devit test 1 1 (0/1) (n_(d) − 1)/d_(RT)− 0.0021 (0.269 − 0.12 * Ti) (n_(d) − 1)/d_(RT) − −0.0029 (0.274 −0.12 * Ti) n_(d) − (1.571 + 0.0085 0.083 * d_(RT)) Predicted andcalculated properties T_(i) 0.6047 0.5634 0.5552 0.5843 0.5799 0.62140.6161 0.6117 P_(n) [for n_(d)] 2.0079 2.0119 2.0002 2.0011 2.00382.0022 2.0053 2.0075 P_(ref) [for (n_(d) − cm³/g 0.1975 0.202 0.20580.2034 0.2018 0.2004 0.1988 0.1975 1)/d_(RT)] P_(Tg) [for T_(g)] ° C.707.8 681.7 696.1 686.6 701.8 674.2 690.8 704.2 P_(d) [for d_(RT)] g/cm³5.1082 5.0701 4.8875 4.9591 4.9913 5.0522 5.0848 5.1096 P_(ref) − (0.269− 0.0011 6.500E−04 0.0034 0.0045 0.0024 0.0059 0.0037 0.0019 0.12 *T_(i)) P_(ref) − (0.274 − −0.0039 −0.0044 −0.0016 −4.700E−04 −0.00269.400E−04 −0.0013 −0.0031 0.12 * T_(i)) P_(n) − (1.571 + 0.0129 0.02010.0235 0.0184 0.0186 0.0119 0.0122 0.0124 0.083 * P_(d)) Exemplary Glass17 18 19 20 21 22 23 24 Composition - mol. % B₂O₃ mol. % 31.32 30.2229.19 29.66 27.95 28.46 28.89 30.21 WO₃ mol. % 6.50 10.94 15.04 10.1119.98 14.76 10.59 10.92 La₂O₃ mol. % 19.97 19.97 19.97 19.96 19.98 19.9719.97 21.96 TiO₂ mol. % 16.97 16.98 16.97 16.97 16.98 16.98 16.98 19.95Nb₂O₅ mol. % 12.72 10.51 8.46 6.84 5.99 4.43 3.18 10.51 SiO₂ mol. % 5.374.24 3.23 4.72 1.99 3.57 4.81 6.27 Bi₂O₃ mol. % 0 0 0 4.59 0 4.68 8.44 0ZrO₂ mol. % 6.98 6.99 6.99 6.99 6.98 6.99 6.99 0 CeO₂ mol. % 0.12 0.110.12 0.12 0.12 0.12 0.12 0.14 CaO mol. % 0.0288 0.0293 0.0298 0.0310.0304 0.0316 0.0326 0.0296 Ta₂O₅ mol. % 0.011 0.0112 0.0076 0.00790.0039 0.004 0.0041 0.0113 Composition constraints TiO₂ + Nb₂O₅ mol. %29.72 27.50 25.45 23.82 22.99 21.42 20.17 30.49 RE₂O₃ + ZrO₂ + mol. %63.24 65.48 67.53 60.97 70.01 63.22 57.80 63.46 TiO₂ + Nb₂O₅ + WO₃ WO₃ +TiO₂ mol. % 23.48 27.93 32.02 27.10 36.98 31.76 27.59 30.89 R₂O + ROmol. % 0.02880 0.02933 0.02982 0.03104 0.03040 0.03163 0.03262 0.02960TiO₂ − SiO₂ mol. % 11.61 12.74 13.75 12.25 15.00 13.41 12.18 13.70B₂O₃ + SiO₂ − mol. % 36.72 34.48 32.44 34.40 29.95 32.05 33.71 36.50P₂O₅ SiO₂ + GeO₂ mol. % 5.376 4.243 3.229 4.722 1.986 3.572 4.811 6.271Measured properties n_(d) 1.997 2.0002 d_(RT) g/cm³ 4.866 4.997 5.1265.306 5.260 5.446 5.593 (n_(d) − 1)/d_(RT) cm³/g 0.20489 0.19016 (n_(d)− 1)/d_(RT) − −5.500E−04 0.0017 (0.269 − 0.12 * T_(i)) (n_(d) −1)/d_(RT) − −0.0055 −0.0033 (0.274 − 0.12 * T_(i)) n_(d) − (1.571 +0.0221 −0.0073 0.083 * d_(RT)) Predicted and calculated properties T_(i)0.5297 0.5796 0.6228 0.6089 0.6714 0.6609 0.6507 0.519 P_(n) [for n_(d)]2.0075 2.0078 2.008 2.0209 2.0083 2.0215 2.0323 2.0078 P_(ref) [for(n_(d) − cm³/g 0.2121 0.2056 0.1996 0.1953 0.1924 0.1882 0.1849 0.20671)/d_(RT)] P_(Tg) [for T_(g)] ° C. 688.0 680.6 673.9 656.6 665.7 648.4634.6 682.4 P_(d) [for d_(RT)] g/cm³ 4.7991 4.9536 5.0961 5.3011 5.26775.4703 5.6342 4.9232 P_(ref) − (0.269 − 0.0066 0.0061 0.0053 −6.800E−040.0039 −0.0015 −0.0060 −3.200E−05 0.12 * T_(i)) P_(ref) − (0.274 −0.0016 0.0011 3.300E−04 −0.0057 −0.0011 −0.0065 −0.0110 −0.0050 0.12 *T_(i)) P_(n) − (1.571 + 0.0381 0.0256 0.0140 0.0100 3.400E−05 −0.0036−0.0063 0.0281 0.083 * P_(d)) Exemplary Glass 25 26 27 28 29 30 31 32Composition - mol. % B₂O₃ mol. % 27.96 27.05 27.96 26.39 27.12 27.9525.76 26.49 WO₃ mol. % 13.97 16.71 16.58 18.68 18.90 18.53 20.57 20.70La₂O₃ mol. % 19.98 19.97 19.97 19.97 19.97 19.97 19.97 19.97 TiO₂ mol. %15.97 15.98 14.23 15.97 14.39 12.95 15.98 14.42 Nb₂O₅ mol. % 8.98 7.778.98 6.89 7.85 8.98 6.05 7.04 SiO₂ mol. % 6.00 5.37 5.13 4.94 4.63 4.474.53 4.24 ZrO₂ mol. % 6.99 6.99 6.99 7.00 6.98 6.99 6.99 6.98 CeO₂ mol.% 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 CaO mol. % 0.0296 0.03 0.03040.0303 0.0306 0.0309 0.0305 0.0309 Ta₂O₅ mol. % 0.0075 0.0076 0.00770.0077 0.0078 0.0078 0.0039 0.0078 Composition constraints TiO₂ + Nb₂O₅mol. % 24.96 23.76 23.23 22.88 22.25 21.95 22.05 21.47 RE₂O₃ + ZrO₂ +mol. % 65.99 67.52 66.85 68.61 68.20 67.52 69.66 69.22 TiO₂ + Nb₂O₅ +WO₃ WO₃ + TiO₂ mol. % 29.96 32.71 30.83 34.67 33.31 31.50 36.57 35.13R₂O + RO mol. % 0.02963 0.03001 0.03037 0.03028 0.03065 0.03092 0.030530.03090 TiO₂ − SiO₂ mol. % 9.97 10.61 9.110 11.04 9.761 8.486 11.4610.19 B₂O₃ + SiO₂ − mol. % 33.97 32.45 33.11 31.36 31.77 32.44 30.3130.75 P₂O₅ SiO₂ + GeO₂ mol. % 6.001 5.377 5.130 4.945 4.634 4.473 4.5314.239 Measured properties n_(d) 1.9867 d_(RT) g/cm³ 5.062 5.240 5.2605.193 5.290 (n_(d) − 1)/d_(RT) cm³/g 0.19492 15 − min devit test 1 1 1(0/1) (n_(d) − 1)/d_(RT) − 4.800E−04 (0.269 − 0.12 * T_(i)) (n_(d) −1)/d_(RT) − −0.0045 (0.274 − 0.12 * T_(i)) n_(d) − (1.571 + −0.00450.083 * d_(RT)) Predicted and calculated properties T_(i) 0.6214 0.64770.6522 0.6662 0.6734 0.6747 0.6832 0.6895 P_(n) [for n_(d)] 2.00222.0042 2.0057 2.0056 2.0073 2.0086 2.007 2.0087 P_(ref) [for (n_(d) −cm³/g 0.2004 0.1967 0.1972 0.1941 0.194 0.1948 0.1916 0.1916 1)/d_(RT)]P_(Tg) [for T_(g)] ° C. 674.2 669.9 668.3 666.8 664.8 663.9 663.8 662.0P_(d) [for d_(RT)] g/cm³ 5.0522 5.151 5.1547 5.2221 5.2381 5.232 5.29065.3035 P_(ref) − (0.269 − 0.0059 0.0055 0.0064 0.0051 0.0058 0.00670.0046 0.0054 0.12 * T_(i)) P_(ref) − (0.274 − 9.400E−04 4.700E−040.0014 4.800E−05 8.400E−04 0.0017 −4.300E−04 3.800E−04 0.12 * T_(i))P_(n) − (1.571 + 0.0119 0.0057 0.0069 0.0012 0.0016 0.0033 −0.0032−0.0025 0.083 * P_(d)) Exemplary Glass 33 34 35 36 37 38 39 40Composition - mol. % B₂O₃ mol. % 27.11 27.96 24.96 25.78 26.41 27.0727.95 27.95 WO₃ mol. % 20.66 20.45 22.96 22.96 22.95 22.96 22.97 22.97La₂O₃ mol. % 19.97 19.97 19.96 19.96 19.96 19.97 19.97 19.97 TiO₂ mol. %13.20 11.65 15.98 14.35 13.08 11.77 9.98 9.98 Nb₂O₅ mol. % 7.86 8.994.99 6.08 6.92 7.79 8.99 8.99 SiO₂ mol. % 4.04 3.84 4.00 3.73 3.52 3.293.00 3.00 ZrO₂ mol. % 6.99 6.98 6.99 6.99 6.99 7.00 7.00 7.00 CeO₂ mol.% 0.12 0.12 0.12 0.12 0.12 0.11 0.12 0.12 CaO mol. % 0.0311 0.03140.0308 0.0312 0.0315 0.0318 0.0322 0.0322 Ta₂O₅ mol. % 0.0079 0.0080.0039 0.004 0.008 0.0081 0.0082 0.0082 Composition constraints TiO₂ +Nb₂O₅ mol. % 21.08 20.65 20.98 20.43 20.01 19.58 18.98 18.98 RE₂O₃ +ZrO₂ + mol. % 68.79 68.14 70.98 70.44 70.01 69.59 68.99 68.99 TiO₂ +Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 33.88 32.12 38.96 37.33 36.06 34.75 32.9632.96 R₂O + RO mol. % 0.03116 0.03146 0.03086 0.03122 0.03149 0.031780.03217 0.03217 TiO₂ − SiO₂ mol. % 9.170 7.814 11.98 10.63 9.560 8.4876.981 6.981 B₂O₃ + SiO₂ − mol. % 31.17 31.82 28.98 29.53 29.95 30.3730.97 30.97 P₂O₅ SiO₂ + GeO₂ mol. % 4.042 3.846 4.003 3.729 3.526 3.2923.003 3.003 Measured properties n_(d) 1.9889 d_(RT) g/cm³ 5.261 5.3605.355 5.331 5.317 (n_(d) − 1)/d_(RT) cm³/g 0.18599 15 − min devit test 11 1 (0/1) T_(liq) ° C. 1077.0 T_(g) ° C. 641.50 n_(d) − (1.437 + 0.01340.0005 * T_(liq)) n_(d) − (1.481 + −0.0306 0.0005 * T_(liq)) (n_(d) −1)/d_(RT) − 0.004 (0.269 − 0.12 * T_(i)) (n_(d) − 1)/d_(RT) − −0.001(0.274 − 0.12 * T_(i)) n_(d) − (1.571 + −0.0234 0.083 * d_(RT))Predicted and calculated properties T_(i) 0.6933 0.6966 0.7042 0.70970.714 0.7185 0.7247 0.7247 P_(n) [for n_(d)] 2.0098 2.0111 2.0087 2.01022.0115 2.0129 2.0147 2.0147 P_(ref) [for (n_(d) − cm³/g 0.1919 0.19240.1884 0.1886 0.1888 0.189 0.1893 0.1893 1)/d_(RT)] P_(Tg) [for T_(g)] °C. 660.8 659.5 660.0 658.3 657.0 655.7 653.9 653.9 P_(d) [for d_(RT)]g/cm³ 5.3079 5.3074 5.3768 5.385 5.391 5.3982 5.4074 5.4074 P_(ref) −(0.269 − 0.0061 0.0070 0.0039 0.0048 0.0055 0.0062 0.0072 0.0072 0.12 *T_(i)) P_(ref) − (0.274 − 0.0011 0.0020 −0.0011 −2.200E−04 4.800E−040.0012 0.0022 0.0022 0.12 * T_(i)) P_(n) − (1.571 + −0.0017 −4.000E−04−0.0086 −0.0077 −0.0070 −0.0062 −0.0051 −0.0051 0.083 * P_(d)) ExemplaryGlass 41 42 43 44 45 46 47 48 Composition - mol. % B₂O₃ mol. % 26.7227.96 25.84 27.95 21.27 21.18 21.60 27.97 WO₃ mol. % 26.34 25.93 28.7328.11 14.41 19.46 19.32 13.99 La₂O₃ mol. % 21.50 20.86 22.59 21.52 20.9520.95 20.95 19.99 TiO₂ mol. % 9.97 7.01 9.99 4.84 14.30 10.25 11.3515.98 Nb₂O₅ mol. % 6.23 8.98 4.26 8.99 9.48 9.48 9.48 8.99 SiO₂ mol. %2.09 2.12 1.43 1.44 8.78 7.66 8.17 5.97 ZrO₂ mol. % 6.99 6.99 6.99 6.997.36 7.17 7.18 6.99 Y₂O₃ mol. % 0 0 0 0 0.38 0.43 0.21 0 BaO mol. % 0 00 0 2.87 3.20 1.53 0.0108 CeO₂ mol. % 0.13 0.12 0.13 0.12 0.12 0.13 0.130 SrO mol. % 0 0 0 0 0.0167 0.0175 0.0173 0 CaO mol. % 0.0329 0.03340.0334 0.0343 0.0309 0.0323 0.032 0.0592 SrCl₄ mol. % 0 0 0 0 0 0 00.0391 Na₂O mol. % 0 0 0 0 0.0279 0.0292 0.0289 0 Ta₂O₅ mol. % 0.00420.0085 0.0042 0.0087 0.0078 0.0082 0.0081 0.0075 Composition constraintsTiO₂ + Nb₂O₅ mol. % 16.21 16.00 14.25 13.84 23.79 19.74 20.84 24.97RE₂O₃ + ZrO₂ + mol. % 71.14 69.86 72.67 70.55 66.98 67.85 68.59 65.94TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 36.33 32.95 38.74 32.97 28.72 29.7330.69 29.97 R₂O + RO mol. % 0.03290 0.03339 0.03341 0.03430 2.943 3.2831.610 0.07005 TiO₂ − SiO₂ mol. % 7.889 4.890 8.558 3.400 5.516 2.5943.182 10.02 B₂O₃ + SiO₂ − mol. % 28.83 30.09 27.30 29.40 30.07 28.8629.79 33.94 P₂O₅ SiO₂ + GeO₂ mol. % 2.088 2.119 1.434 1.441 8.788 7.6638.177 5.969 Measured properties d_(RT) g/cm³ 5.487 5.419 5.617 5.4915.090 15 − min devit test 1 1 1 (0/1) T_(liq) ° C. 1082.0 T_(g) ° C.653.70 Predicted and calculated properties T_(i) 0.7719 0.7708 0.80370.8037 0.6425 0.7069 0.6949 0.6213 P_(n) [for n_(d)] 2.0163 2.02032.0175 2.0248 2.0282 2.0317 2.0294 2.0023 P_(ref) [for (n_(d) − cm³/g0.1802 0.1833 0.1738 0.179 0.1965 0.1893 0.1921 0.2004 1)/d_(RT)] P_(Tg)[for T_(g)] ° C. 654.7 649.8 655.3 646.9 681.2 668.7 668.8 674.3 P_(d)[for d_(RT)] g/cm³ 5.6163 5.582 5.7646 5.712 5.2913 5.493 5.4257 5.0529P_(ref) − (0.269 − 0.0039 0.0068 0.0013 0.0064 0.0046 0.0051 0.00650.0059 0.12 * T_(i)) P_(ref) − (0.274 − −0.0011 0.0018 −0.0037 0.0014−3.900E−04 8.200E−05 0.0015 9.300E−04 0.12 * T_(i)) P_(n) − (1.571 +−0.0208 −0.0140 −0.0320 −0.0203 0.0181 0.0048 0.0081 0.0119 0.083 *P_(d)) Exemplary Glass 49 50 51 52 53 54 55 56 Composition - mol. % B₂O₃mol. % 27.02 27.98 26.36 27.09 27.97 25.73 26.47 27.10 WO₃ mol. % 16.8616.67 18.84 19.04 18.64 20.71 20.81 20.77 La₂O₃ mol. % 19.99 19.98 19.9819.99 19.99 19.99 19.98 19.99 TiO₂ mol. % 15.99 14.20 15.98 14.38 12.8715.99 14.44 13.21 Nb₂O₅ mol. % 7.72 8.99 6.83 7.82 8.99 6.01 7.00 7.83SiO₂ mol. % 5.32 5.07 4.89 4.58 4.42 4.47 4.18 3.98 ZrO₂ mol. % 6.996.99 7.00 6.99 7.00 6.99 7.00 6.99 BaO mol. % 0.011 0.0111 0.0111 0.01120.0113 0.0112 0.0113 0.0114 CaO mol. % 0.06 0.0607 0.0606 0.0613 0.06190.0611 0.0618 0.0623 SiCl₄ mol. % 0.0396 0.0401 0.04 0.0405 0.04080.0403 0.0408 0.0411 Ta₂O₅ mol. % 0.0076 0.0077 0.0077 0.0078 0.00780.0039 0.0078 0.0079 Composition constraints TiO₂ + Nb₂O₅ mol. % 23.7023.18 22.82 22.20 21.87 22.00 21.44 21.04 RE₂O₃ + ZrO₂ + mol. % 67.5466.83 68.63 68.21 67.49 69.68 69.23 68.79 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂mol. % 32.85 30.87 34.82 33.42 31.52 36.70 35.25 33.98 R₂O + RO mol. %0.07098 0.07183 0.07162 0.07252 0.07316 0.07223 0.07307 0.07370 TiO₂ −SiO₂ mol. % 10.67 9.124 11.09 9.798 8.458 11.52 10.26 9.226 B₂O₃ + SiO₂− mol. % 32.34 33.05 31.25 31.67 32.39 30.20 30.65 31.08 P₂O₅ SiO₂ +GeO₂ mol. % 5.321 5.073 4.888 4.578 4.416 4.474 4.180 3.983 Measuredproperties d_(RT) g/cm³ 5.209 5.182 5.287 5.299 5.221 5.346 5.361 5.32815 − min devit test 1 1 1 1 (0/1) T_(liq) ° C. 1075.0 1095.0 1108.01065.0 T_(g) ° C. 651.80 645.80 Predicted and calculated propertiesT_(i) 0.649 0.6531 0.6676 0.6746 0.676 0.6843 0.6903 0.6941 P_(n) [forn_(d)] 2.0044 2.0059 2.0058 2.0076 2.0087 2.0073 2.0089 2.0101 P_(ref)[for (n_(d) − cm³/g 0.1965 0.1971 0.1939 0.1939 0.1946 0.1914 0.19150.1917 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 669.7 668.2 666.6 664.6 663.7663.7 661.9 660.7 P_(d) [for d_(RT)] g/cm³ 5.1569 5.1584 5.2282 5.2445.2369 5.2964 5.3077 5.3128 P_(ref) − (0.269 − 0.0054 0.0064 0.00500.0058 0.0067 0.0045 0.0054 0.0060 0.12 * T_(i)) P_(ref) − (0.274 −4.300E−04 0.0014 6.800E−06 8.200E−04 0.0017 −4.700E−04 3.500E−04 0.00100.12 * T_(i)) P_(n) − (1.571 + 0.0054 0.0068 8.500E−04 0.0014 0.0031−0.0033 −0.0026 −0.0019 0.083 * P_(d)) Exemplary Glass 57 58 59 60 61 6263 64 Composition - mol. % B₂O₃ mol. % 27.97 24.97 25.78 26.41 27.0627.96 31.41 29.82 WO₃ mol. % 20.54 22.99 22.98 22.98 22.98 22.98 11.4015.38 La₂O₃ mol. % 19.98 19.99 19.98 19.99 19.98 19.98 19.98 19.99 TiO₂mol. % 11.62 15.98 14.39 13.12 11.82 10.00 16.98 16.98 Nb₂O₅ mol. % 8.995.00 6.06 6.90 7.78 8.99 10.29 8.30 SiO₂ mol. % 3.79 3.97 3.70 3.50 3.262.97 2.83 2.42 ZrO₂ mol. % 6.99 6.99 7.00 6.99 7.00 6.99 7.00 7.00 BaOmol. % 0.0115 0.0113 0.0114 0.0115 0.0116 0.0118 0.0108 0.0109 CaO mol.% 0.0629 0.0617 0.0624 0.0629 0.0635 0.0643 0.0588 0.0597 SiCl₄ mol. %0.0415 0.0407 0.0412 0.0416 0.0419 0.0424 0.0388 0.0394 Ta₂O₅ mol. %0.008 0.0039 0.004 0.008 0.0081 0.0082 0.0112 0.0076 Compositionconstraints TiO₂ + Nb₂O₅ mol. % 20.61 20.98 20.45 20.02 19.59 18.9927.26 25.28 RE₂O₃ + ZrO₂ + mol. % 68.11 70.94 70.41 69.97 69.55 68.9465.64 67.64 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 32.15 38.97 37.37 36.1034.80 32.97 28.38 32.35 R₂O + RO mol. % 0.07442 0.07297 0.07379 0.074440.07513 0.07605 0.06952 0.07062 TiO₂ − SiO₂ mol. % 7.829 12.01 10.699.627 8.555 7.027 14.15 14.55 B₂O₃ + SiO₂ − mol. % 31.76 28.94 29.4729.91 30.32 30.93 34.24 32.24 P₂O₅ SiO₂ + GeO₂ mol. % 3.788 3.973 3.6973.495 3.260 2.970 2.825 2.424 Measured properties d_(RT) g/cm³ 5.2815.397 5.392 5.403 5.363 5.322 15 − min devit test 1 1 1 1 1 (0/1)T_(liq) ° C. 1116.0 1100.0 1077.0 T_(g) ° C. 647.50 645.70 641.50Predicted and calculated properties T_(i) 0.6974 0.7043 0.7096 0.71390.7183 0.7245 0.5847 0.6263 P_(n) [for n_(d)] 2.0113 2.0089 2.01042.0116 2.013 2.0148 2.0072 2.0077 P_(ref) [for (n_(d) − cm³/g 0.19230.1884 0.1886 0.1888 0.189 0.1893 0.2046 0.1989 1)/d_(RT)] P_(Tg) [forT_(g)] ° C. 659.4 660.0 658.4 657.1 655.8 653.9 679.7 673.3 P_(d) [ford_(RT)] g/cm³ 5.3112 5.3789 5.3863 5.3924 5.3993 5.4078 4.9674 5.1072P_(ref) − (0.269 − 0.0070 0.0039 0.0048 0.0054 0.0062 0.0072 0.00580.0051 0.12 * T_(i)) P_(ref) − (0.274 − 0.0020 −0.0011 −2.500E−044.400E−04 0.0012 0.0022 7.900E−04 9.600E−05 0.12 * T_(i)) P_(n) −(1.571 + −4.900E−04 −0.0086 −0.0077 −0.0070 −0.0061 −0.0051 0.02390.0128 0.083 * P_(d)) Exemplary Glass 65 66 67 68 69 70 71 72Composition - mol. % B₂O₃ mol. % 27.98 28.97 30.67 30.75 32.09 32.3832.19 33.66 WO₃ mol. % 19.99 15.99 12.11 15.99 8.86 12.22 15.98 5.29La₂O₃ mol. % 19.99 19.98 19.98 19.99 19.98 19.99 19.98 19.99 TiO₂ mol. %16.98 16.97 16.98 12.67 16.98 12.72 9.16 16.97 Nb₂O₅ mol. % 5.99 9.9911.44 12.79 12.66 14.15 15.06 14.01 SiO₂ mol. % 1.96 0.97 1.71 0.71 2.311.41 0.51 2.97 ZrO₂ mol. % 7.00 7.00 6.99 6.99 6.99 7.00 6.99 6.99 BaOmol. % 0.0111 0.0112 0.011 0.0115 0.0108 0.0113 0.0118 0.0106 CaO mol. %0.0608 0.0613 0.06 0.0631 0.059 0.0619 0.0646 0.0578 SiCl₄ mol. % 0.04010.0405 0.0396 0.0417 0.0389 0.0408 0.0426 0.0382 Ta₂O₅ mol. % 0.00390.0078 0.0114 0.012 0.0112 0.0118 0.0123 0.0147 Composition constraintsTiO₂ + Nb₂O₅ mol. % 22.97 26.97 28.42 25.45 29.64 26.87 24.21 30.98RE₂O₃ + ZrO₂ + mol. % 69.95 69.93 67.50 68.42 65.48 66.08 67.17 63.25TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 36.97 32.96 29.09 28.65 25.84 24.9425.14 22.26 R₂O + RO mol. % 0.07189 0.07249 0.07099 0.07463 0.069770.07316 0.07636 0.06842 TiO₂ − SiO₂ mol. % 15.02 16.00 15.27 11.96 14.6711.31 8.643 14.00 B₂O₃ + SiO₂ − mol. % 29.93 29.95 32.38 31.45 34.4033.80 32.70 36.63 P₂O₅ SiO₂ + GeO₂ mol. % 1.957 0.9723 1.708 0.70662.312 1.414 0.5121 2.969 Measured properties d_(RT) g/cm³ 5.202 4.9725.084 5.165 4.877 15 − min devit test 1 1 1 (0/1) T_(liq) ° C. 1107.01111.0 1106.0 1039.0 1137.0 Predicted and calculated properties T_(i)0.6716 0.6144 0.5789 0.628 0.5473 0.5933 0.6395 0.5101 P_(n) [for n_(d)]2.0083 2.031 2.0248 2.0346 2.0197 2.0285 2.0374 2.0142 P_(ref) [for(n_(d) − cm³/g 0.1923 0.2021 0.2067 0.2027 0.2105 0.2071 0.2031 0.21471)/d_(RT)] P_(Tg) [for T_(g)] ° C. 665.8 674.5 680.2 670.0 685.1 675.7666.4 690.4 Pd [for d_(RT)l g/cm³ 5.2684 5.1781 5.0295 5.1986 4.90625.0546 5.2146 4.7702 P_(ref) − (0.269 − 0.0039 0.0068 0.0072 0.00900.0072 0.0093 0.0109 0.0069 0.12 * T_(i)) P_(ref) − (0.274 − −0.00110.0018 0.0022 0.0040 0.0022 0.0043 0.0059 0.0019 0.12 * T_(i)) P_(n) −(1.571 + −2.200E−05 0.0302 0.0363 0.0321 0.0415 0.0380 0.0336 0.04720.083 * P_(d)) Exemplary Glass 73 74 75 76 77 78 79 80 Composition -mol. % B₂O₃ mol. % 33.83 33.86 33.75 35.96 35.96 35.97 35.96 32.60 WO₃mol. % 9.08 12.09 15.98 0 4.75 8.23 11.63 13.40 La₂O3 mol. % 19.98 19.9819.98 19.98 19.98 19.99 19.98 20.90 TiO₂ mol. % 12.53 9.26 5.39 16.9811.94 8.24 4.64 13.11 Nb₂O₅ mol. % 15.45 16.44 17.49 15.98 17.46 18.5619.61 12.93 SiO₂ mol. % 2.02 1.24 0.28 3.98 2.79 1.89 1.06 0.0584 ZrO₂mol. % 7.00 7.00 7.00 7.00 6.99 6.99 6.99 6.99 BaO mol. % 0.0111 0.01160.0121 0.0103 0.0109 0.0114 0.0119 0 CaO mol. % 0.0609 0.0633 0.06610.0561 0.0598 0.0625 0.065 0 SiCl₄ mol. % 0.0402 0.0418 0.0437 0.03710.0395 0.0412 0.0429 0 Ta₂O₅ mol. % 0.0155 0.0161 0.0168 0.0142 0.01520.0159 0.0165 0.0119 Composition constraints TiO₂ + Nb₂O₅ mol. % 27.9825.70 22.88 32.97 29.40 26.80 24.25 26.04 RE₂O₃ + ZrO₂ + mol. % 64.0364.77 65.84 59.94 61.12 62.01 62.84 67.33 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂mol. % 21.60 21.35 21.37 16.98 16.69 16.47 16.26 26.51 R₂O + RO mol. %0.07204 0.07483 0.07823 0.06639 0.07070 0.07387 0.07693 0 TiO₂ − SiO₂mol. % 10.51 8.019 5.108 13.00 9.148 6.348 3.572 13.05 B₂O3 + SiO₂ −mol. % 35.84 35.10 34.02 39.94 38.75 37.86 37.03 32.66 P₂O₅ SiO₂ + GeO₂mol. % 2.018 1.240 0.2778 3.981 2.789 1.894 1.062 0.05839 Measuredproperties d_(RT) g/cm³ 4.992 5.065 5.130 15 − min devit test (0/1) 1 11 1 1 1 1 1 Predicted and calculated properties T_(i) 0.563 0.60320.6525 0.450 0.519 0.5678 0.6141 0.6133 P_(n) [for n_(d)] 2.0236 2.03112.0404 2.0057 2.0173 2.026 2.0341 2.0312 P_(ref) [for (n_(d) − cm³/g0.2108 0.2077 0.2036 0.221 0.216 0.2124 0.2088 0.2032 1)/d_(RT)] P_(Tg)[for T_(g)] ° C. 680.1 672.3 662.5 698.2 686.0 677.0 668.2 678.0 P_(d)[for d_(RT)] g/cm³ 4.9346 5.0654 5.2322 4.5678 4.7728 4.9235 5.06885.1496 P_(ref) − (0.269 − 0.0094 0.0111 0.0129 0.0060 0.0093 0.01150.0135 0.0078 0.12 * T_(i)) P_(ref) − (0.274 − 0.0044 0.0061 0.00799.700E−04 0.0043 0.0065 0.0085 0.0028 0.12 * T_(i)) P_(n) − (1.571 +0.0430 0.0397 0.0352 0.0556 0.0502 0.0463 0.0424 0.0328 0.083 * P_(d))Exemplary Glass 81 82 83 84 85 86 87 88 Composition - mol. % B₂O₃ mol. %31.04 32.93 29.65 31.39 33.10 29.76 33.04 32.66 WO₃ mol. % 15.61 10.9317.60 13.24 9.15 15.54 8.73 9.54 La₂O₃ mol. % 18.25 21.10 15.87 18.4821.03 15.67 21.58 21.21 TiO₂ mol. % 17.09 14.89 20.67 18.72 16.63 22.9815.88 16.95 Nb₂O₅ mol. % 10.94 13.08 9.15 11.11 13.03 9.00 13.11 12.61SiO₂ mol. % 0.0562 0.0574 0.0542 0.0552 0.0564 0.0529 0.0568 0.0565 ZrO₂mol. % 7.00 7.00 7.00 6.99 7.00 7.00 7.60 6.96 Ta₂O₅ mol. % 0.01150.0117 0.0074 0.0113 0.0115 0.0072 0.0116 0.0115 Composition constraintsTiO₂ + Nb₂O₅ mol. % 28.03 27.97 29.82 29.83 29.66 31.98 28.99 29.56RE₂O₃ + ZrO₂ + mol. % 68.89 67.00 70.29 68.54 66.84 70.18 66.89 67.27TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 32.70 25.82 38.27 31.96 25.78 38.5124.61 26.50 TiO₂ − SiO₂ mol. % 17.03 14.83 20.62 18.66 16.57 22.92 15.8316.90 B₂O₃ + SiO₂ − mol. % 31.10 32.99 29.71 31.45 33.15 29.81 33.1032.72 P₂O₅ SiO₂ + GeO₂ mol. % 0.05616 0.05738 0.05415 0.05524 0.056390.05285 0.05676 0.05649 Measured properties d_(RT) g/cm³ 5.071 5.0895.036 5.034 4.974 15 − min devit test 1 1 1 1 1 1 1 1 (0/1) Predictedand calculated properties T_(i) 0.5931 0.5825 0.5757 0.5647 0.55630.5443 0.5667 0.5605 P_(n) [for n_(d)] 2.0236 2.0321 2.0166 2.02442.0318 2.0162 2.0336 2.0329 P_(ref) [for (n_(d) − cm³/g 0.2062 0.20640.2089 0.2091 0.2091 0.2124 0.2079 0.2083 1)/d_(RT)] P_(Tg) [for T_(g)]° C. 667.2 684.9 657.5 673.9 689.4 662.6 692.5 689.9 P_(d) [for d_(RT)]g/cm³ 5.0455 5.072 4.9513 4.9728 5.0006 4.860 5.0354 5.0251 P_(ref) −(0.269 − 0.0084 0.0073 0.0090 0.0079 0.0069 0.0087 0.0069 0.0065 0.12 *T_(i)) P_(ref) − (0.274 − 0.0034 0.0023 0.0040 0.0029 0.0019 0.00370.0019 0.0015 0.12 * T_(i)) P_(n) − (1.571 + 0.0338 0.0401 0.0347 0.04070.0458 0.0418 0.0447 0.0448 0.083 * P_(d)) Exemplary Glass 89 90 91 9293 94 95 96 Composition - mol. % B₂O₃ mol. % 33.33 32.27 32.96 33.5332.53 33.12 33.72 32.59 WO₃ mol. % 7.88 10.35 8.69 7.29 9.55 8.13 6.6713.39 La₂O₃ mol. % 21.84 20.86 21.49 22.02 21.09 21.63 22.20 20.89 TiO₂mol. % 16.27 18.02 17.30 16.64 18.55 17.90 17.23 13.13 Nb₂O₅ mol. %13.33 12.12 12.85 13.47 12.30 12.93 13.58 12.93 SiO₂ mol. % 0.05660.0562 0.0564 0.0565 0.0561 0.0562 0.0563 0.0584 ZrO₂ mol. % 7.28 6.326.65 6.97 5.90 6.22 6.54 7.00 Ta₂O₅ mol. % 0.0116 0.0115 0.0115 0.01150.0114 0.0115 0.0115 0.0119 Composition constraints TiO₂ + Nb₂O₅ mol. %29.60 30.14 30.15 30.11 30.86 30.83 30.81 26.06 RE₂O₃ + ZrO₂ + mol. %66.60 67.66 66.97 66.40 67.40 66.81 66.21 67.34 TiO₂ + Nb₂O + WO₃ WO₃ +TiO₂ mol. % 24.15 28.36 25.98 23.94 28.10 26.03 23.89 26.51 TiO₂ − SiO₂mol. % 16.21 17.96 17.24 16.59 18.50 17.84 17.17 13.07 B₂O₃ + SiO₂ −mol. % 33.39 32.33 33.02 33.59 32.59 33.18 33.78 32.65 P₂O₅ SiO₂ + GeO₂mol. % 0.05663 0.05623 0.05637 0.05652 0.05605 0.05619 0.05634 0.05837Measured properties d_(RT) g/cm³ 5.083 15 − min devit test 1 1 1 1 1 1 11 (0/1) Predicted and calculated properties T_(i) 0.5555 0.5545 0.54980.5465 0.5422 0.5386 0.5347 0.613 P_(n) [for n_(d)] 2.0344 2.0324 2.03382.0349 2.0331 2.0343 2.0356 2.0313 P_(ref) [for (n_(d) − cm³/g 0.20880.2086 0.2091 0.2095 0.2096 0.210 0.2105 0.2032 1)/d_(RT)] P_(Tg) [forT_(g)] ° C. 695.0 687.4 692.5 696.8 689.7 694.1 698.6 678.0 P_(d) [ford_(RT)] g/cm³ 5.0154 5.0158 5.0061 4.9994 4.9933 4.986 4.9789 5.1491P_(ref) − (0.269 − 0.0065 0.0062 0.0061 0.0061 0.0057 0.0057 0.00560.0078 0.12 * T_(i)) P_(ref) − (0.274 − 0.0015 0.0012 0.0011 0.00116.900E−04 6.700E−04 6.400E−04 0.0028 0.12 * T_(i)) P_(n) − (1.571 +0.0472 0.0451 0.0473 0.0490 0.0477 0.0495 0.0514 0.0329 0.083 * P_(d))Exemplary Glass 97 98 99 100 101 102 103 104 Composition - mol. % B₂O₃mol. % 31.69 32.86 31.05 31.98 33.06 30.41 31.33 32.14 WO₃ mol. % 14.6811.72 15.59 13.10 10.44 16.45 14.02 11.93 La₂O₃ mol. % 19.96 21.21 19.3020.30 21.43 18.66 19.64 20.51 TiO₂ mol. % 15.44 14.08 17.06 16.17 14.8318.63 17.75 16.90 Nb₂O₅ mol. % 11.77 13.07 10.94 11.97 13.18 10.15 11.1612.06 SiO₂ mol. % 0.0288 0.0579 0.0286 0.0286 0.0575 0.0283 0.02840.0284 ZrO₂ mol. % 4.85 6.98 3.33 4.97 6.99 1.88 3.49 4.94 BaO mol. %1.54 0 2.62 1.45 0 3.65 2.50 1.46 SiO mol. % 0.0334 0 0.0497 0.0332 00.0821 0.0493 0.033 Na₂O mol. % 0 0 0.0277 0 0 0.0274 0.0275 0 Ta₂O₅mol. % 0.0118 0.0118 0.0117 0.0117 0.0117 0.0077 0.0116 0.0116 Al₂O₃mol. % 0 0 0 0 0 0.0167 0 0 Composition constraints TiO₂ + Nb₂O₅ mol. %27.21 27.16 28.00 28.13 28.01 28.79 28.91 28.95 RE₂O₃ + ZrO₂ + mol. %66.70 67.07 66.21 66.50 66.88 65.77 66.05 66.32 TiO₂ + Nb₂O₅ + WO₃ WO₃ +TiO₂ mol. % 30.12 25.80 32.64 29.26 25.27 35.08 31.77 28.82 R₂O + ROmol. % 1.570 0 2.696 1.480 0 3.759 2.578 1.493 TiO₂ − SiO₂ mol. % 15.4114.02 17.03 16.14 14.77 18.60 17.72 16.87 B₂O₃ + SiO₂ − mol. % 31.7232.92 31.08 32.01 33.11 30.44 31.36 32.17 P₂O₅ SiO₂ + GeO₂ mol. %0.02883 0.05787 0.02856 0.02862 0.05747 0.02831 0.02836 0.02843 Measuredproperties d_(RT) g/cm³ 5.124 5.079 5.164 5.115 5.073 5.117 5.120 5.06415 − min devit test 1 1 1 1 1 1 1 1 (0/1) Predicted and calculatedproperties T_(i) 0.5921 0.5951 0.5771 0.5769 0.5811 0.5624 0.5623 0.5635P_(n) [for n_(d)] 2.0271 2.0322 2.024 2.0283 2.0329 2.0211 2.0253 2.029P_(ref) [for (n_(d) − cm³/g 0.2029 0.2049 0.2026 0.2044 0.2063 0.20240.2042 0.2057 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 671.4 683.1 666.7 676.5687.1 662.3 671.8 680.1 P_(d) [for d_(RT)] g/cm³ 5.1269 5.108 5.11035.0914 5.0762 5.0942 5.0761 5.062 P_(ref) − (0.269 − 0.0049 0.00740.0028 0.0047 0.0070 8.400E−04 0.0026 0.0043 0.12 * T_(i)) P_(ref) −(0.274 − −9.800E−05 0.0024 −0.0022 −3.500E−04 0.0020 −0.0042 −0.0024−7.200E−04 0.12 * T_(i)) P_(n) − (1.571 + 0.0306 0.0372 0.0288 0.03470.0406 0.0273 0.0330 0.0379 0.083 * P_(d)) Exemplary Glass 105 106 107108 109 110 111 112 Composition - mol. % B₂O₃ mol. % 33.24 29.63 32.2833.53 34.98 34.07 33.47 33.41 WO₃ mol. % 9.12 17.58 10.59 7.29 9.99 9.9912.98 10.00 La₂O₃ mol. % 21.68 17.84 20.67 22.01 20.98 20.98 20.99 20.99TiO₂ mol. % 15.60 20.65 17.94 16.66 9.99 13.02 10.29 15.19 Nb₂O₅ mol. %13.30 9.13 12.07 13.46 16.99 14.87 15.20 13.35 SiO₂ mol. % 0.0571 0.0280.0282 0.0565 0.0592 0.0579 0.0596 0.057 ZrO₂ mol. % 6.98 0 4.74 6.977.00 7.00 6.99 7.00 BaO mol. % 0 4.99 1.60 0 0 0 0 0 SiO mol. % 0 0.09740.0327 0 0 0 0 0 Na₂O mol. % 0 0.0271 0.0273 0 0 0 0 0 Ta₂O₅ mol. %0.0116 0.0076 0.0115 0.0115 0.0161 0.0118 0.0122 0.0116 Al₂O₃ mol. % 00.0165 0 0 0 0 0 0 Composition constraints TiO₂ + Nb₂O₅ mol. % 28.9029.78 30.02 30.13 26.98 27.89 25.49 28.54 RE₂O₃ + ZrO₂ + mol. % 66.6965.20 66.02 66.40 64.95 65.86 66.45 66.52 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂mol. % 24.73 38.23 28.54 23.95 19.98 23.01 23.27 25.19 R₂O + RO mol. % 05.114 1.660 0 0 0 0 0 TiO₂ − SiO₂ mol. % 15.55 20.62 17.92 16.61 9.93212.96 10.23 15.13 B₂O₃ + SiO₂ − mol. % 33.30 29.66 32.31 33.58 35.0434.13 33.53 33.47 P₂O₅ SiO₂ + GeO₂ mol. % 0.05706 0.02798 0.028170.05651 0.05917 0.05788 0.05963 0.05697 Measured properties 15 − mindevit test 1 1 1 1 1 1 1 1 (0/1) Predicted and calculated propertiesT_(i) 0.5666 0.5432 0.5453 0.5463 0.5846 0.5765 0.6164 0.571 P_(n) [forn_(d)] 2.0338 2.0174 2.0293 2.0349 2.0381 2.0337 2.0372 2.0305 P_(ref)[for (n_(d) − cm³/g 0.2077 0.202 0.2071 0.2096 0.2091 0.2083 0.20460.2077 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 691.1 656.6 683.9 696.8 681.1684.0 676.5 686.1 P_(d) [for d_(RT)] g/cm³ 5.0441 5.0739 5.0231 4.99885.0602 5.0415 5.1619 5.0287 P_(ref) − (0.269 − 0.0067 −0.0018 0.00360.0061 0.0102 0.0085 0.0096 0.0073 0.12 * T_(i)) P_(ref) − (0.274 −0.0017 −0.0068 −0.0014 0.0011 0.0052 0.0035 0.0046 0.0023 0.12 * T_(i))P_(n) − (1.571 + 0.0442 0.0252 0.0414 0.0490 0.0471 0.0442 0.0378 0.04210.083 * P_(d)) Exemplary Glass 113 114 115 116 117 118 119 120Composition - mol. % B₂O₃ mol. % 32.76 32.40 32.78 32.19 31.78 31.3531.00 30.57 WO₃ mol. % 12.73 15.17 9.99 12.69 14.73 17.29 14.96 17.11La₂O₃ mol. % 20.99 20.99 20.98 20.99 20.99 20.99 20.99 20.99 TiO₂ mol. %13.05 10.51 17.31 15.04 13.21 10.72 15.52 13.59 Nb₂O₅ mol. % 13.41 13.8911.87 12.02 12.23 12.62 10.49 10.71 SiO₂ mol. % 0.0584 0.03 0.05610.0576 0.0294 0.0301 0.0289 0.0295 ZrO₂ mol. % 6.99 7.00 7.00 7.00 7.007.00 7.00 7.00 Ta₂O₅ mol. % 0.0119 0.0122 0.0114 0.0117 0.012 0.01230.0079 0.008 Composition constraints TiO₂ + Nb₂O₅ mol. % 26.46 24.4029.18 27.07 25.45 23.34 26.01 24.30 RE₂O₃ + ZrO₂ + mol. % 67.16 67.5667.15 67.74 68.17 68.61 68.96 69.39 TiO₂ + Nb₂O₅ + WO₃ WO3 + TiO2 mol. %25.78 25.68 27.30 27.73 27.95 28.01 30.48 30.70 TiO₂ − SiO₂ mol. % 12.9910.48 17.26 14.99 13.18 10.69 15.49 13.56 B₂O₃ + SiO₂ − mol. % 32.8232.43 32.84 32.25 31.81 31.38 31.03 30.60 P₂O₅ SiO₂ + GeO₂ mol. %0.05841 0.02998 0.05607 0.05756 0.02937 0.03014 0.02890 0.02952 Measuredproperties 15 − min devit test 1 1 1 1 1 1 1 1 (0/1) Predicted andcalculated properties T_(i) 0.6061 0.6389 0.5655 0.6005 0.6268 0.65980.6228 0.6499 P_(n) [for n_(d)] 2.0332 2.0366 2.0274 2.0302 2.03282.0358 2.0292 2.0316 P_(ref) [for (n_(d) − cm³/g 0.2043 0.2013 0.20720.2038 0.2013 0.1981 0.2003 0.1977 1)/d_(RT)] P_(Tg) [for T_(g)] ° C.679.6 673.2 688.1 681.6 676.5 669.8 678.3 672.9 P_(d) [for d_(RT)] g/cm³5.1361 5.2364 5.015 5.1224 5.2048 5.3074 5.1978 5.2837 P_(ref) − (0.269− 0.0080 0.0090 0.0061 0.0069 0.0075 0.0083 0.0061 0.0067 0.12 * T_(i))P_(ref) − (0.274 − 0.0030 0.0040 0.0011 0.0019 0.0025 0.0033 0.00110.0017 0.12 * T_(i)) P_(n) − (1.571 + 0.0359 0.0310 0.0401 0.0341 0.02980.0243 0.0267 0.0221 0.083 * P_(d)) Exemplary Glass 121 122 123 124 125126 127 128 Composition - mol. % B₂O₃ mol. % 29.99 33.00 28.25 31.8524.76 27.51 30.98 21.37 WO₃ mol. % 19.99 13.00 13.00 13.00 13.00 13.0013.00 13.00 La₂O₃ mol. % 20.99 21.00 21.01 19.28 21.00 19.42 17.99 21.00TiO₂ mol. % 11.00 13.00 12.99 13.00 13.01 13.00 13.01 13.00 Nb₂O₅ mol. %11.00 13.00 13.01 13.00 13.00 13.00 13.00 13.00 SiO₂ mol. % 0.0303 04.74 0 8.24 4.42 0 11.64 ZrO₂ mol. % 7.00 7.01 7.00 6.99 7.00 7.01 7.007.00 Y₂O₃ mol. % 0 0 0 2.86 0 2.64 5.02 0 Ta₂O₅ mol. % 0.0083 0 0 0 0 00 0 Composition constraints TiO₂ + Nb₂O₅ mol. % 22.00 26.00 26.00 26.0126.00 25.99 26.01 26.00 RE₂O₃ + ZrO₂ + mol. % 69.98 67.00 67.01 68.1567.00 68.07 69.02 67.00 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 30.99 26.0025.99 26.01 26.00 26.00 26.01 26.00 TiO₂ − SiO₂ mol. % 10.97 13.00 8.25113.00 4.766 8.575 13.01 1.363 B₂O₃ + SiO₂ − mol. % 30.02 33.00 32.9931.85 33.00 31.93 30.98 33.00 P₂O₅ SiO₂ + GeO₂ mol. % 0.03034 0 4.739 08.239 4.421 0 11.64 Measured properties d_(RT) g/cm³ 5.019 5.076 5.1765.123 15 − min devit test 1 1 1 (0/1) T_(liq) ° C. 1063.0 1089.0 1110.01184.0 1133.0 Predicted and calculated properties T_(i) 0.6857 0.6120.6121 0.6016 0.6119 0.6027 0.5936 0.6119 P_(n) [for n_(d)] 2.035 2.02972.0323 2.0349 2.034 2.0369 2.0389 2.0358 P_(ref) [for (n_(d) − cm³/g0.1941 0.2032 0.2042 0.2048 0.2049 0.2056 0.2061 0.2056 1)/d_(RT)]P_(Tg) [for T_(g)] ° C. 665.7 678.8 679.6 683.8 680.1 684.2 687.7 680.7P_(d) [for d_(RT)l g/cm³ 5.399 5.1384 5.1498 5.1311 5.1565 5.1424 5.1265.1638 P_(ref) − (0.269 − 0.0074 0.0077 0.0086 0.0080 0.0094 0.00890.0083 0.0101 0.12 * T_(i)) P_(ref) − (0.274 − 0.0024 0.0027 0.00360.0030 0.0044 0.0039 0.0033 0.0051 0.12 * T_(i)) P_(n) − (1.571 + 0.01580.0322 0.0339 0.0381 0.0350 0.0391 0.0425 0.0362 0.083 * P_(d))Exemplary Glass 129 130 131 132 133 134 135 136 Composition - mol. %B₂O₃ mol. % 24.26 26.72 30.14 30.64 32.98 31.99 30.98 33.99 WO₃ mol. %13.00 13.00 13.00 5.99 13.00 12.99 13.99 9.99 La₂O₃ mol. % 19.44 18.2316.71 19.96 19.99 21.00 20.99 19.98 TiO₂ mol. % 13.00 13.00 12.99 16.979.99 13.50 16.00 11.99 Nb₂O₅ mol. % 13.00 13.00 13.00 8.74 16.99 13.4910.99 16.98 SiO₂ mol. % 7.70 4.42 0 5.77 0.03 0.0293 0.0288 0.0584 Bi₂O₃mol. % 0 0 0 4.77 0 0 0 0 ZrO₂ mol. % 7.00 7.00 7.00 6.99 7.00 6.99 7.006.99 Y₂O₃ mol. % 2.60 4.62 7.17 0 0 0 0 0 CeO₂ mol. % 0 0 0 0.12 0 0 0 0CaO mol. % 0 0 0 0.0306 0 0 0 0 Ta₂O₅ mol. % 0 0 0 0.0078 0.0163 0.0120.0118 0.0159 Composition constraints TiO₂ + Nb₂O₅ mol. % 26.00 26.0025.99 25.73 26.98 26.99 26.99 28.97 RE₂O₃ + ZrO₂ + mol. % 68.05 68.8669.86 58.76 66.97 67.97 68.97 65.94 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. %26.00 26.00 25.99 22.98 22.99 26.49 29.99 21.98 R₂O + RO mol. % 0 0 00.03062 0 0 0 0 TiO₂ − SiO₂ mol. % 5.301 8.578 12.99 11.21 9.959 13.4715.97 11.93 B₂O₃ + SiO₂ − mol. % 31.95 31.14 30.14 36.43 33.01 32.0131.01 34.04 P₂O₅ SiO₂ + GeO₂ mol. % 7.695 4.423 0 5.773 0.02998 0.029320.02881 0.05838 Measured properties d_(RT) g/cm³ 5.200 5.030 5.058 5.1274.996 15 − min devit test 1 1 1 (0/1) T_(liq) ° C. 1030.0 1072.0 1099.01062.0 Predicted and calculated properties T_(i) 0.6027 0.5952 0.58540.5616 0.5971 0.6029 0.6087 0.5606 P_(n) [for n_(d)] 2.0386 2.04062.0428 2.0214 2.0474 2.0391 2.0326 2.0425 P_(ref) [for (n_(d) − cm³/g0.2063 0.2067 0.2072 0.2008 0.2092 0.2049 0.2023 0.2127 1)/d_(RT)lP_(Tg) [for T_(g)] ° C. 684.7 687.8 691.5 662.4 673.1 680.3 680.7 679.7P_(d) [for d_(RT)] g/cm³ 5.1495 5.1372 5.1206 5.1731 5.1284 5.15755.1705 5.0065 P_(ref) − (0.269 − 0.0096 0.0092 0.0085 −7.600E−04 0.01190.0083 0.0064 0.0110 0.12 * T_(i)) P_(ref) − (0.274 − 0.0046 0.00420.0035 −0.0058 0.0069 0.0033 0.0014 0.0060 0.12 * T_(i)) P_(n) −(1.571 + 0.0402 0.0432 0.0468 0.0210 0.0508 0.0400 0.0324 0.0560 0.083 *P_(d)) Exemplary Glass 137 138 139 140 141 142 143 144 Composition -mol. % B₂O₃ mol. % 33.48 32.97 34.98 33.98 33.97 32.99 32.00 31.99 WO₃mol. % 9.99 10.00 7.00 7.00 6.99 15.99 15.99 15.99 La₂O₂ mol. % 19.9819.98 19.99 19.98 19.98 20.00 19.99 19.99 TiO₂ mol. % 13.98 16.00 12.9915.99 18.00 8.99 9.00 10.00 Nb₂O₅ mol. % 15.49 13.99 17.99 15.99 13.9915.00 15.99 14.99 SiO₂ mol. % 0.0575 0.0566 0.0575 0.0562 0.055 0.03010.0304 0.0301 ZrO₂ mol. % 6.99 6.99 6.99 6.99 7.00 6.99 6.99 6.99 Ta₂O₅mol. % 0.0156 0.0115 0.0156 0.0153 0.015 0.0123 0.0166 0.0123Composition constraints TiO₂ + Nb₂O₅ mol. % 29.48 29.99 30.97 31.9831.99 23.99 24.99 24.99 RE₂O₃ + ZrO₂ + mol. % 66.45 66.96 64.95 65.9565.96 66.97 67.96 67.97 TiO₂ + Nb₂O₅ + WO₃ WO₃ + TiO₂ mol. % 23.98 25.9919.98 22.99 24.99 24.99 24.99 25.99 TiO₂ − SiO₂ mol. % 13.93 15.94 12.9315.94 17.94 8.964 8.968 9.966 B₂O3 + SiO₂ − mol. % 33.54 33.03 35.0434.03 34.02 33.02 32.03 32.02 P₂O₅ SiO₂ + GeO₂ mol. % 0.05747 0.056560.05745 0.05624 0.05501 0.03012 0.03044 0.03013 Measured propertiesd_(RT) g/cm³ 4.968 4.986 4.896 4.893 4.892 5.133 5.154 5.147 T_(liq) °C. 1066.0 1083.0 1064.0 1089.0 1103.0 Predicted and calculatedproperties T_(i) 0.5564 0.5521 0.5231 0.5151 0.5151 0.6418 0.6323 0.6324P_(n) [for n_(d)] 2.0384 2.0343 2.043 2.0398 2.0297 2.035 2.0469 2.0419P_(ref) [for (n_(d) − cm³/g 0.212 0.2113 0.2171 0.2166 0.2148 0.20270.2048 0.2039 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 681.5 683.3 685.7 688.7690.0 665.9 667.1 667.7 P_(d) [for d_(RT)] g/cm³ 4.9917 4.9768 4.90054.8843 4.8561 5.2082 5.2342 5.2206 P_(ref) − (0.269 − 0.0098 0.00860.0109 0.0094 0.0076 0.0107 0.0117 0.0108 0.12 * T_(i)) P_(ref) − (0.274− 0.0048 0.0036 0.0059 0.0044 0.0026 0.0057 0.0067 0.0058 0.12 * T_(i))P_(n) − (1.571 + 0.0531 0.0503 0.0652 0.0634 0.0556 0.0317 0.0415 0.03760.083 * P_(d)) Exemplary Glass 145 146 147 Composition - mol. % B₂O₃mol. % 30.98 30.99 28.99 WO₃ mol. % 16.99 16.99 17.99 La₂O₃ mol. % 19.9919.99 19.99 TiO₂ mol. % 9.01 9.99 10.00 Nb₂O₅ mol. % 15.99 14.99 15.99SiO₂ mol. % 0.0307 0.0304 0.031 ZrO₂ mol. % 6.99 7.00 7.00 Ta₂O₅ mol. %0.0167 0.0124 0.0169 Composition constraints TiO₂ + Nb₂O₅ mol. % 25.0024.99 25.99 RE₂O₃ + ZrO₂ + mol. % 68.97 68.97 70.96 TiO₂ + Nb₂O₅ + WO₃WO₃ + TiO₂ mol. % 26.00 26.99 27.99 TiO₂ − SiO₂ mol. % 8.977 9.963 9.969B₂O₃ + SiO₂ − mol. % 31.01 31.02 29.02 P₂O₅ SiO₂ + GeO₂ mol. % 0.030710.03040 0.03099 Measured properties d_(RT) g/cm³ 5.189 5.183 5.245Predicted and calculated properties T_(i) 0.6375 0.6377 0.6338 P_(n)[for n_(d)] 2.0532 2.0481 2.0663 P_(ref) [for (n_(d) − cm³/g 0.20450.2036 0.2054 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 666.1 666.7 666.9 P_(d)[for d_(RT)] g/cm³ 5.2831 5.2692 5.3438 P_(ref) − (0.269 − 0.0120 0.01110.0125 0.12 * T_(i)) P_(ref) − (0.274 − 0.0070 0.0061 0.0075 0.12 *T_(i)) P_(n) − (1.571 + 0.0438 0.0398 0.0517 0.083 * P_(d))

Table 7 below lists the glass compositions and properties forComparative Glasses C1-C44.

TABLE 7 Compositions and Properties of Comparative Example GlassesComparative Examples C1 C2 C3 C4 C5 C6 C7 C8 Reference [4] [10] [5] [8][6] [9] [3] [2] Composition - mol. % La₂O₃ mol. % 9.71 14.49 13.29 20.0820.11 25.60 10.68 12.13 TiO₂ mol. % 21.73 3.97 3.33 31.67 31.71 23.998.54 3.57 B₂O₃ mol. % 24.37 11.38 23.36 13.05 12.95 19.81 26.67 31.18BaO mol. % 10.47 0 0 0 0 0 0 0 Nb₂O₅ mol. % 4.32 7.15 7.85 4.85 4.854.50 0.71 6.91 WO₃ mol. % 4.45 7.79 13.28 4.12 4.12 3.00 11.39 5.08 ZrO₂mol. % 6.89 5.92 3.33 7.60 7.61 6.80 0.36 3.58 Y₂O₃ mol. % 3.73 9.120.83 0.35 0.35 4.50 0 0 SiO₂ mol. % 9.78 16.62 3.32 12.99 12.99 11.811.43 3.58 GeO₂ mol. % 3.24 0 0 0 0 0 0 0 MgO mol. % 1.30 0 0 0 0 0 0 0ZnO mol. % 0 21.42 28.09 2.38 2.38 0 35.95 30.40 Gd₂O₃ mol. % 0 2.14 02.90 2.91 0 4.27 0 Ta₂O₅ mol. % 0 0 3.33 0 0 0 0 3.58 Measuredproperties n_(d) 1.9109 1.852 1.968 2.060 2.060 2.000 1.9041 1.9127d_(RT) g/cm³ 5.400 5.230 5.230 5.100 5.280 4.990 (n_(d) − 1)/d_(RT)cm³/g 0.17926 0.20268 0.20268 0.19608 0.17123 0.18291 T_(liq) ° C.990.00 1280.0 1080.0 1260.0 1260.0 1225.0 1000.0 1060.0 T_(g) ° C.638.00 591.00 726.00 726.00 727.00 576.00 593.00 Log(η_(liq)) P 0.40000Predicted and calculated properties P_(n) [for n_(d)] 1.915 1.990 1.9722.049 2.050 2.024 1.906 1.909 P_(ref) [for (n_(d) − cm³/g 0.2042 0.18350.1825 0.2116 0.2116 0.1986 0.1702 0.1845 1)/d_(RT)] P_(Tg) [for T_(g)]° C. 663.1 657.0 585.0 720.2 720.5 744.6 569.4 580.8 P_(d) [for d_(RT)]g/cm³ 4.435 5.511 5.345 5.081 5.085 5.146 5.389 4.897 ComparativeExamples C9 C10 C11 C12 C13 C14 C15 C16 Reference [1] [7] [5] [5] [5][13] [18] [17] Composition - mol. % La₂O₃ mol. % 23.43 22.47 14.44 12.9214.44 15.30 24.93 23.61 TiO₂ mol. % 4.49 13.40 3.49 3.24 3.49 15.8111.82 23.17 B₂O₃ mol. % 31.31 23.76 24.87 22.71 26.36 37.20 32.01 20.96Nb₂O₅ mol. % 4.65 4.37 6.73 4.85 5.23 12.79 1.42 7.25 WO₃ mol. % 3.613.14 13.93 18.47 13.93 0 0 0.44 ZrO₂ mol. % 12.33 7.24 3.49 3.23 3.494.60 11.04 7.10 Y₂O₃ mol. % 2.14 1.06 0 0.81 0 0 0 0.37 SiO₂ mol. % 9.7214.88 1.62 3.23 1.62 2.69 3.14 11.78 GeO₂ mol. % 0 0 0 0 0 4.64 0 0 ZnOmol. % 1.02 5.66 27.58 27.31 27.59 0 0 0 Gd₂O₃ mol. % 4.37 4.02 0 0 00.89 15.63 3.14 Ta₂O₅ mol. % 0 0 3.86 3.23 3.86 5.28 0 0 Yb₂O₃ mol. %2.93 0 0 0 0 0 0 0 Al₂O₃ mol. % 0 0 0 0 0 0.79 0 0 SnO₂ mol. % 0 0 0 0 00 0 0.68 Li₂O mol. % 0 0 0 0 0 0 0 1.50 Sb₂O₃ mol. % 0 0 0 0 0 0 0 0.011Measured properties n_(d) 1.908 1.948 1.968 1.956 1.951 1.970 1.8732.0049 d_(RT) g/cm³ 4.890 5.170 5.480 5.520 5.450 5.250 (n_(d) −1)/d_(RT) cm³/g 0.18569 0.18337 0.17664 0.17319 0.17450 0.16629 T_(liq)° C. 1215.0 1230.0 1080.0 1070.0 1060.0 1320.0 T_(g) ° C. 694.00 592.00587.00 588.00 Predicted and calculated properties P_(n) [for n_(d)]1.962 1.963 1.971 1.959 1.953 1.966 2.015 2.025 P_(ref) [for (n_(d) −cm³/g 0.1684 0.1833 0.1785 0.1748 0.1753 0.2147 0.1574 0.2036 1)/d_(RT)]P_(Tg) [for T_(g)] ° C. 714.3 703.0 585.9 574.5 584.0 673.1 761.9 726.6P_(d) [for d_(RT)] g/cm³ 5.547 5.232 5.399 5.451 5.360 4.376 6.127 5.092Comparative Examples C17 C18 C19 C20 C21 C22 C23 C24 Reference [9] [8][11] [12] [15] [16] [14] [15] Composition - mol. % La₂O₃ mol. % 18.6022.55 22.52 20.35 21.76 22.49 21.67 16.65 TiO₂ mol. % 27.00 27.07 27.1614.17 22.14 26.05 16.97 18.77 B₂O₃ mol. % 22.21 15.58 15.57 39.48 16.4521.37 28.51 38.96 Nb₂O₅ mol. % 6.00 5.52 5.52 1.83 6.02 5.36 7.19 5.10WO₃ mol. % 0 0 0 16.04 0 0 3.44 0 ZrO₂ mol. % 6.51 9.09 9.02 5.25 8.757.27 7.13 7.41 Y₂O₃ mol. % 0 0 0 2.15 7.46 0.38 0 4.11 SiO₂ mol. % 11.1911.58 11.57 0 12.61 12.07 8.92 5.95 ZnO mol. % 0 1.48 1.48 0 0 2.64 0 0Gd₂O₃ mol. % 4.80 4.88 4.92 0 4.65 2.38 0 2.99 Ta₂O₅ mol. % 0 2.26 2.240.73 0 0 0.0079 0 Li₂O mol. % 3.69 0 0 0 0 0 0 0 As₂O₃ mol. % 0 0 0 00.17 0 0 0.0722 Bi₂O₃ mol. % 0 0 0 0 0 0 6.01 0 CeO₂ mol. % 0 0 0 0 0 00.13 0 CaO mol. % 0 0 0 0 0 0 0.031 0 Measured properties n_(d) 2.0002.0451 2.0451 1.933 2.0233 2.0034 1.923 d_(RT) g/cm³ 4.900 5.420 5.4205.300 5.030 4.570 (n_(d) − 1)/d_(RT) cm³/g 0.20408 0.19282 0.192820.19308 0.19948 0.20197 T_(liq) ° C. 1200.0 1250.0 1250.0 1190.0 T_(g) °C. 698.00 746.00 746.00 706.00 Log(η_(liq)) P 0.40000 Predicted andcalculated properties P_(n) [for n_(d)] 1.999 2.065 2.065 1.929 2.0542.008 2.022 1.919 P_(ref) [for (n_(d) − cm³/g 0.2097 0.2029 0.203 0.17960.199 0.2046 0.1963 0.1995 1)/d_(RT)] P_(Tg) [for T_(g)] ° C. 702.2740.0 740.0 668.1 762.4 724.0 667.0 703.3 P_(d) [for d_(RT)] g/cm³ 4.8225.285 5.285 5.010 5.363 4.961 5.285 4.524 Comparative Examples C25 C26C27 C28 C29 C30 C31 C32 Reference [19] [9] [9] [9] [20] [27] [25] [21]Composition - mol. % La₂O₃ mol. % 19.33 22.50 22.70 22.33 12.25 27.2324.55 15.51 TiO₂ mol. % 20.74 24.99 23.99 24.03 8.34 0 0 0 B₂O₃ mol. %20.54 24.70 28.50 19.82 38.60 27.32 33.75 40.00 Nb₂O₅ mol. % 5.94 4.304.00 3.50 7.26 0 8.31 16.98 WO₃ mol. % 0 0.20 0.20 4.50 2.99 18.23 15.063.51 ZrO₂ mol. % 7.06 7.00 6.00 6.61 5.40 13.61 6.18 9.01 Y₂O₃ mol. %1.55 3.50 4.00 4.41 1.77 0 0.71 0 SiO₂ mol. % 12.46 12.81 10.61 11.801.11 0 0 0 ZnO mol. % 3.57 0 0 0 21.24 0 0 14.99 Gd₂O₃ mol. % 8.81 0 03.00 0 0 2.48 0 Ta₂O₅ mol. % 0 0 0 0 1.05 13.61 8.90 0 Sb₂O₃ mol. % 0 00 0 0 0 0.0674 0.0106 Measured properties n_(d) 1.9886 1.980 1.960 2.0001.8994 1.9813 1.953 1.9482 d_(RT) g/cm³ 5.100 4.800 4.800 5.200 5.940(n_(d) − 1)/d_(RT) cm³/g 0.19384 0.20417 0.20000 0.19231 0.16044 T_(liq)° C. 1125.0 1125.0 1225.0 1040.0 T_(g) ° C. 703.00 717.00 708.00 729.00605.00 679.00 Log(η_(liq)) P 0.80000 0.70000 0.40000 Predicted andcalculated properties P_(n) [for n_(d)] 2.022 1.976 1.964 2.018 1.8922.042 2.039 1.955 P_(ref) [for (n_(d) − cm³/g 0.1942 0.2043 0.20150.1959 0.1936 0.148 0.1668 0.2021 1)/d_(RT)] P_(Tg) [for T_(g)] ° C.727.2 729.1 728.0 735.8 612.5 687.4 681.8 629.8 P_(d) [for d_(RT)] g/cm³5.358 4.737 4.717 5.212 4.596 5.976 5.726 4.809 Comparative Example C33C34 C35 C36 C37 C38 C39 C40 Reference [23] [22] [24] [1] [5] [2] [26][5] Composition - mol. % La₂O₃ mol. % 17.13 20.17 15.64 15.66 13.2612.31 9.70 12.92 TiO₂ mol. % 20.06 15.56 23.34 0 2.80 3.64 7.95 8.79B₂O₃ mol. % 39.04 30.61 30.35 39.80 23.73 31.67 39.59 22.71 BaO mol. % 00 1.62 0 0 0 0 0 Nb₂O₅ mol. % 0 0 1.87 10.68 5.49 10.13 2.42 4.85 WO₃mol. % 11.67 3.83 1.61 2.60 12.09 2.04 3.78 12.91 ZrO₂ mol. % 6.05 4.326.05 15.61 6.07 3.63 10.14 3.23 Y₂O₃ mol. % 0 0 0 6.09 0 0 0 0.81 SiO₂mol. % 0 0 4.13 4.46 2.92 3.64 4.31 3.24 ZnO mol. % 0 0 15.27 4.60 26.0130.87 12.71 27.31 Gd₂O₃ mol. % 0 0 0 0 0.36 0 5.19 0 Ta₂O₅ mol. % 6.054.42 0 0.51 7.28 2.07 0 3.23 Li₂O mol. % 0 0 0 0 0 0 4.22 0 Sb₂O₃ mol. %0 0 0.13 0 0 0 0 0 HfO₂ mol. % 0 21.09 0 0 0 0 0 0 Measured propertiesn_(d) 1.9466 1.9661 1.9468 1.815 1.958 1.920 1.860 1.970 d_(RT) g/cm³4.650 4.450 5.450 4.820 4.230 5.370 (n_(d) − 1)/d_(RT) cm³/g 0.203610.18315 0.17578 0.19087 0.20331 0.18063 T_(liq) ° C. 1140.0 1180.01070.0 1130.0 T_(g) ° C. 623.00 598.00 590.00 597.00 591.00 Predictedand calculated properties P_(n) [for n_(d)] 1.929 1.957 1.919 1.9201.974 1.919 1.841 1.963 P_(ref) [for (n_(d) − cm³/g 0.1875 0.1836 0.19860.1915 0.1767 0.1926 0.1829 0.1836 1)/d_(RT)] P_(Tg) [for T_(g)] ° C.659.4 683.1 651.8 678.5 589.6 587.5 606.7 590.2 P_(d) [for d_(RT)] g/cm³4.650 4.948 4.605 4.737 5.336 4.827 4.589 5.250 Comparative Examples C41C42 C43 C44 Reference [2] [2] [2] [2] Composition - mol. % La₂O₃ mol. %12.36 12.41 12.31 12.32 TiO₂ mol. % 1.30 2.09 2.07 2.06 B₂O₃ mol. %31.79 31.92 31.29 31.68 Nb₂O₅ mol. % 10.18 9.43 8.97 8.57 WO₃ mol. %1.26 2.05 1.26 1.25 ZrO₂ mol. % 3.64 3.66 3.63 4.42 SiO₂ mol. % 3.663.67 3.63 3.63 ZnO mol. % 33.35 31.11 32.44 32.44 Ta₂O₅ mol. % 2.47 3.663.63 3.63 CaO mol. % 0 0 0.77 0 Measured properties n_(d) 1.9107 1.91711.9126 1.9114 d_(RT) g/cm³ 4.850 4.930 4.930 4.920 (n_(d) − 1)/d_(RT)cm³/g 0.18777 0.18602 0.18511 0.18524 T_(liq) ° C. 1150.0 1060.0 1100.01150.0 T_(g) ° C. 588.00 593.00 590.00 592.00 Predicted and calculatedproperties P_(n) [for n_(d)] 1.914 1.917 1.914 1.911 P_(ref) [for (n_(d)− cm³/g 0.1893 0.1886 0.1879 0.1869 1)/d_(RT)] P_(Tg) [for T_(g)] ° C.581.9 585.1 584.2 584.4 P_(d) [for d_(RT)] g/cm³ 4.869 4.853 4.859 4.856

The reference key for each of the Comparative Glasses listed in Table 7is as follows: [1]U.S. Ser. No. 10/287,205B2; [2] U.S. Pat. No.8,575,048B2; [3] U.S. Pat. No. 8,609,560B2; [4] U.S. Pat. No.8,835,336B2; [5] U.S. Pat. No. 9,255,028B2; [6]U.S. Pat. No.9,302,930B2; [7] U.S. Pat. No. 9,394,194B2; [8] U.S. Pat. No.9,643,880B2; [9] WO2020045417A1; [10] WO2020062009A1; [11]JP2020073453A; [12] JP52129716A; [13] JPH09278480; [14] U.S. ProvisionalPatent Application Ser. No. 63/076,551; [15] U.S. Pat. No. 4,584,279A;[16] U.S. Pat. No. 8,728,963B2; [17] WO2012099168A1; [18]WO2020034215A1; [19] U.S. Pat. No. 8,661,853B2; [20] CN101215082; [21]CN104583142B; [22] JPS534023; [23] U.S. Pat. No. 4,268,312A; [24]U.S.Pat. No. 8,404,606B2; [25] U.S. Pat. No. 8,476,177B2; [26] US2015225282;[27] Imaoka M., Yamazaki T., Refractive index and Abbes number of glassof lanthanum borate system, J. Ceram. Assoc. Jpn, 1962, vol. 70, No. 5,p. 115-123.

Glasses with high refractive indexes, such as n_(d)=2.0 or like, aretypically characterized with high liquidus temperatures, which mayreduce the liquidus viscosity and, therefore, cause crystallization ofmelts when cooling. Also, glasses with high liquidus temperatures shouldbe melted at higher temperatures to avoid crystallization, which maycause the loss of transmittance and/or require longer bleachingprocedure. Therefore, the lower the liquidus temperature at a givenvalue of the refractive index, the better the characteristics of theresulting glasses are, and the higher the glass formability may beexpected from these glasses. Accordingly, high refractive index at lowerliquidus temperature identifies the advantage of a given glasscomposition comparing to its analogs with higher liquidus temperaturesand/or lower refractive indexes.

FIG. 7 is a plot showing the relationship between the liquidustemperature T_(liq) and the refractive index parameter P_(n) for some ofthe Exemplary Glasses and some of the Comparative Glasses. The ExemplaryGlasses (filled circles) are the Examples 1, 40, 48, 50 to 53, 58, 60,62, 66, 67, 69, 71, 72, 122, 123, 125, 127, 128 and 133 to 141 fromTable 6. The Comparative Glasses (open circles) are the Examples C1 toC10 from Table 7. The refractive index parameter P_(n) was determinedaccording to Formula (II). All of the Exemplary Glasses and ComparativeGlasses shown in FIG. 7 have the features specified in Table 8. In Table8, the specification “Not limited” refers to a limitation that was notconsidered when selecting the compositions.

TABLE 8 Limitations for glass compositions shown in FIG. 7 Quantity UnitMin Max WO₃ mol. % 3 35 TiO₂ mol. % 0.3 50 Nb₂O₅ mol. % 0.3 50 Bi₂O₃mol. % 0 20 TeO₂ mol. % 0 10 PbO mol. % 0 5 MoO₃ mol. % 0 3 V₂O₅ mol. %0 1 TiO₂ + Nb₂O₅ mol. % 0.6 60 F + Cl + Br + I mol. % 0 3 B₂O₃ + SiO₂ −P₂O₅ mol. % 0 Not limited P_(n) 1.9 Not limited T_(liq) ° C. Not limited1350

The above-enumerated Comparative Glasses were selected as having thehighest refractive index parameter P_(n) at comparable values ofliquidus temperature T_(liq) among the known glasses that have thefeatures specified in Table 8.

The line corresponding to the formula y=1.437+0.0005*x shown in FIG. 7provides a distinction between the Comparative Glasses having thefeatures specified in Table 8 and the Exemplary Glasses 1, 40, 48, 50 to53, 58, 60, 62, 66, 67, 69, 71, 72, 122, 123, 125, 127, 128 and 133 to141 according to the present disclosure. As can be seen in FIG. 7, thementioned Exemplary Glasses (filled circles) and none of the ComparativeGlasses (open circles) represented in FIG. 7 fall above the liney=1.437+0.0005*x, where y corresponds to the refractive index parameterP_(n) and x corresponds to the liquidus temperature T_(liq). In otherwords, some of the Exemplary Glasses and none of the Comparative Glassesrepresented in FIG. 7 satisfy the following formula (VI)(a):

P _(n)−(1.437+0.0005*T _(liq))>0.00  (VI)(a)

As can also be seen in FIG. 7, some of Exemplary Glasses and none of theComparative Glasses represented in FIG. 7 fall above the liney=1.481+0.0005*x, where y corresponds to the refractive index parameterP_(n) and x corresponds to the liquidus temperature T_(liq). In otherwords, some of the Exemplary Glasses and none of the Comparative Glassesrepresented in FIG. 7 satisfy the following formula (VI)(b):

P _(n)−(1.481+0.0005*T _(liq))>0.00  (VI)(b)

The Exemplary Examples represented in FIG. 7 are, by prediction,superior in terms of the combination of T_(liq) and n_(d) to the bestknown Comparative Glasses that have the features specified in Table 8.

FIG. 8 is a plot showing the relationship between the liquidustemperature T_(liq) and n_(d) for some of the Exemplary Glasses and someof the Comparative Glasses. The Exemplary Glasses (filled circles) arethe Examples 1 and 40 from Table 6. The Comparative Glasses (opencircles) are the Examples C1, C3 to C8 and C11 to C13 from Table 7. Allof the Exemplary Glasses and Comparative Glasses shown in FIG. 8 havethe features specified in Table 9. In Table 9, the specification “Notlimited” refers to a limitation that was not considered when selectingthe compositions.

TABLE 9 Limitations for glass compositions shown in FIG. 8 Quantity UnitMin Max WO₃ mol. % 3 35 TiO₂ mol. % 0.3 50 Nb₂O₅ mol. % 0.3 50 Bi₂O₃mol. % 0 20 TeO₂ mol. % 0 10 PbO mol. % 0 5 MoO₃ mol. % 0 3 V₂O₅ mol. %0 1 TiO₂ + Nb₂O₅ mol. % 0.6 60 F + Cl + Br + I mol. % 0 3 B₂O₃ + SiO₂ −P₂O₅ mol. % 0 Not limited n_(d) 1.9 Not limited T_(liq) ° C. Not limited1350

The above-enumerated Comparative Glasses were selected as having thehighest measured values of n_(d) at comparable values of the liquidustemperature T_(liq) among the known glasses that have the mentionedfeatures specified in Table 9.

The line corresponding to the formula y=1.437+0.0005*x shown in FIG. 8provides a distinction between the Comparative Glasses having thefeatures specified in Table 9 and the Exemplary Glasses 1 and 40according to the present disclosure. As can be seen in FIG. 8, thementioned Exemplary Glasses (filled circles) and none of the ComparativeGlasses (open circles) represented in FIG. 8 fall above the liney=1.437+0.0005*x, where y corresponds to n_(d) and x corresponds toT_(liq). In other words, some of the Exemplary Glasses and none of theComparative Glasses represented in FIG. 8 satisfy the following formula(VII)(a):

n _(d)−(1.437+0.0005*T _(liq))>0.00  (VII)(a)

As can also be seen in FIG. 8, some of Exemplary Glasses and none of theComparative Glasses represented in FIG. 8 fall above the liney=1.481+0.0005*x, where y corresponds to n_(d) and x corresponds toT_(liq). In other words, the said Exemplary Glasses and none of theComparative Glasses represented in FIG. 8 satisfy the following formula(VII)(b):

n _(d)−(1.481+0.0005*T _(liq))>0.00  (VII)(b)

The Exemplary Examples represented in FIG. 8 are, according tomeasurement, superior in terms of combination of T_(liq) and n_(d) tothe best known Comparative Glasses that have the features specified inTable 9.

TABLE 10 Attributes of Comparative Example Glasses Having the FeaturesSpecified in Tables 8 and 9 Ex. # C1 C2 C3 C4 C5 C6 C7 C8 CompositionNb₂O₅ mol. % 4.32 7.15 7.84 4.86 4.85 4.50 0.71 6.90 TiO₂ mol. % 21.733.97 3.33 31.69 31.69 24.00 8.52 3.57 Bi₂O₃ mol. % 0 0 0 0 0 0 0 0 TeO₂mol. % 0 0 0 0 0 0 0 0 PbO mol. % 0 0 0 0 0 0 0 0 MoO₃ mol. % 0 0 0 0 00 0 0 V₂O₅ mol. % 0 0 0 0 0 0 0 0 TiO₂ + Nb₂O₅ mol. % 26.06 11.12 11.1736.55 36.55 28.50 9.24 10.47 F + Cl + Br + I mol. % 0 0 0 0 0 0 0 0B₂O₃ + SiO₂ − P₂O₅ mol. % 34.08 28.00 26.56 25.90 25.91 31.60 27.9534.60 Measured properties T_(liq) ° C. 990.0 1280 1080 1260 1260 12251000 1060 n_(d) 1.9109 1.852 1.968 2.060 2.060 2.000 1.9041 1.9127 n_(d)− (1.437 + 0.0005 * T_(liq)) −0.0211 −0.225 −0.009 −0.007 −0.007 −0.0495−0.0329 −0.0543 n_(d) − (1.481 + 0.0005 * T_(liq)) −0.0651 −0.269 −0.053−0.051 −0.051 −0.0935 −0.0769 −0.0983 Predicted and calculatedproperties P_(n) 1.9152 1.9895 1.9727 2.0504 2.0504 2.0243 1.9067 1.9095P_(n) − (1.437 + 0.0005 * T_(liq)) −0.0168 −0.0875 −0.0043 −0.0166−0.0166 −0.0252 −0.0303 −0.0575 P_(n) − (1.481 + 0.0005 * T_(liq))−0.0608 −0.1315 −0.0483 −0.0606 −0.0606 −0.0692 −0.0743 −0.1015 Ex. # C9C10 C11 C12 C13 Composition Nb₂O₅ mol. % 4.66 4.37 6.72 4.85 5.23 TiO₂mol. % 4.48 13.39 3.49 3.23 3.49 Bi₂O₃ mol. % 0 0 0 0 0 TeO₂ mol. % 0 00 0 0 PbO mol. % 0 0 0 0 0 MoO₃ mol. % 0 0 0 0 0 V₂O₅ mol. % 0 0 0 0 0TiO₂ + Nb₂O₅ mol. % 9.15 17.77 10.21 8.08 8.71 F + Cl + Br + I mol. % 00 0 0 0 B₂O₃ + SiO₂ − P₂O₅ mol. % 40.77 38.57 26.35 25.82 27.85 Measuredproperties T_(liq) ° C. 1215 1230 1080 1070 1060 n_(d) 1.908 1.948 1.9681.956 1.951 n_(d) − (1.437 + 0.0005 * T_(liq)) −0.1365 −0.104 −0.009−0.016 −0.016 n_(d) − (1.481 + 0.0005 * T_(liq)) −0.1805 −0.148 −0.053−0.060 −0.060 Predicted and calculated properties P_(n) 1.9645 1.96311.9714 1.9591 1.9533 P_(n) − (1.437 + 0.0005 * T_(liq)) −0.0800 −0.0889−0.0056 −0.0129 −0.0137 P_(n) − (1.481 + 0.0005 * T_(liq)) −0.1240−0.1329 −0.0496 −0.0569 −0.0577

In addition to high refractive index and low density, high transmittancein the blue range is also desired for many applications. Glasses withhigh values of refraction at a given transmittance have an advantageover glasses with a lower value of refraction at the same transmittance.

FIG. 9 is a plot showing the relationship between the transmittanceindex T_(i) (a predictor of transmittance in the blue and given byFormula (IV)) and the refraction parameter P_(ref) (a prediction ofrefraction and given by Formula (II)) for some of the Exemplary Glassesand some of the Comparative Glasses. The Exemplary Glasses (filledcircles) are the Examples 1 to 19, 21, 25 to 38, 41, 43, 48 to 61, 63 to74, 76, 77, 80 to 105, 107 to 124, 126, 127, 130, 131 and 133 to 147from Table 6. The Comparative Glasses (open circles) are the ExamplesC14 to C23 from Table 7. All of the Exemplary Glasses and ComparativeGlasses shown in FIG. 9 have the features specified in Table 11. InTable 11, the specification “Not limited” refers to a limitation thatwas not considered when selecting the compositions.

TABLE 11 Limitations for glass compositions shown in FIG. 9 QuantityUnit Min Max TiO₂ mol. % 7.5 28 B₂O₃ mol. % 1 40 Nb₂O₅ mol. % 0.3 19.5WO₃ mol. % 0 35 La₂O₃ mol. % 0 25 Gd₂O₃ mol. % 0 25 Bi₂O₃ mol. % 0 20ZrO₂ mol. % 0 20 TeO₂ mol. % 0 20 SiO₂ mol. % 0 13.5 Al₂O₃ mol. % 0 10ThO₂ mol. % 0 10 GeO₂ mol. % 0 10 Ta₂O₅ mol. % 0 10 PbO mol. % 0 5 V₂O₅mol. % 0 1 F at. % 0 5 Cl at. % 0 1 Br at. % 0 1 I at. % 0 1 RE₂O₃ +ZrO₂ + TiO₂ + Nb₂O₅ + mol. % 10 Not limited WO₃ WO₃ + TiO₂ mol. % Notlimited 40 TiO₂ + Nb₂O₅ mol. % Not limited 35 R₂O + RO mol. % 0 5 TiO₂ −SiO₂ mol. % 7.5 Not limited B₂O₃ + SiO₂ − P₂O₅ mol. % 0 Not limitedP_(n) 1.85 2.1

The above-enumerated Comparative Glasses were selected as having thehighest refraction parameter P_(ref) at comparable values oftransmittance index T_(i) among the known glasses that have the featuresspecified in Table 11.

The line corresponding to the formula y=0.269−0.12*x shown in FIG. 9provides a visual distinction between the Comparative Glasses having thefeatures specified in Table 11 and the Exemplary Glasses 1 to 19, 21, 25to 38, 41, 43, 48 to 61, 63 to 74, 76, 77, 80 to 105, 107 to 124, 126,127, 130, 131 and 133 to 147. As can be seen in FIG. 9, the mentionedExemplary Glasses (filled circles) and none of the Comparative Glasses(open circles) represented in FIG. 9 fall above the line y=0.269−0.12*x,where y corresponds to the refraction parameter P_(ref) and xcorresponds to the transmittance index T_(i). In other words, some ofthe Exemplary Glasses and none of the Comparative Glasses represented inFIG. 9 satisfy the following formula (VIII)(a):

P _(ref)−(0.269−0.12*T _(i))>0.00  (VIII)(a)

As can also be seen in FIG. 9, some of Exemplary Glasses and none of theComparative Glasses represented in FIG. 9 fall above the liney=0.274−0.12*x, where y corresponds to the refraction parameter P_(ref)and x corresponds to the transmittance index T_(i). In other words, someof the Exemplary Glasses and none of the Comparative Glasses representedin FIG. 9 satisfy the following formula (VIII)(b):

P _(ref)−(0.274−0.12*T _(i))>0.00  (VIII)(b)

The Exemplary Examples represented in FIG. 9 are, by prediction,superior in terms of the combination of T_(i) and (n_(d)−1)/d_(RT) tothe best known Comparative Glasses that have the features specified inTable 11.

FIG. 10 is a plot showing the relationship between the transmittanceindex T_(i) and the refractive index to density ratio (“refraction”)(n_(d)−1)/d_(RT) for some of the Exemplary Glasses and some of theComparative Glasses. The Exemplary Glasses (filled circles) are theExamples 1, 14, 21 and 25 from Table 6. The Comparative Glasses (opencircles) are the Examples C15, C17 to C19, C22 and C24 to C28 from Table7. All of the Exemplary Glasses and Comparative Glasses shown in FIG. 10have the features specified in Table 12. In Table 12, the specification“Not limited” refers to a limitation that was not considered whenselecting the compositions.

TABLE 12 Limitations for glass compositions shown in FIG. 10 QuantityUnit Min Max TiO₂ mol. % 7.5 28 B₂O₃ mol. % 1 40 Nb₂O₅ mol. % 0.3 19.5WO₃ mol. % 0 35 La₂O₃ mol. % 0 25 Gd₂O₃ mol. % 0 25 Bi₂O₃ mol. % 0 20ZrO₂ mol. % 0 20 TeO₂ mol. % 0 20 SiO₂ mol. % 0 13.5 Al₂O₃ mol. % 0 10ThO₂ mol. % 0 10 GeO₂ mol. % 0 10 Ta₂O₅ mol. % 0 10 PbO mol. % 0 5 V₂O₅mol. % 0 1 F at. % 0 5 Cl at. % 0 1 Br at. % 0 1 I at. % 0 1 RE₂O₃ +ZrO₂ + TiO₂ + Nb₂O₅ + mol. % 10 Not limited WO₃ WO₃ + TiO₂ mol. % Notlimited 40 TiO₂ + Nb₂O₅ mol. % Not limited 35 R₂O + RO mol. % 0 5 TiO₂ −SiO₂ mol. % 7.5 Not limited B₂O₃ + SiO₂ − P₂O₅ mol. % 0 Not limitedn_(d) 1.85 2.1

The above-enumerated Comparative Glasses were selected as having thehighest measured values of the refractive index to density ratio(“refraction”) (n_(d)−1)/d_(RT) at comparable values of thetransmittance index T_(i) among the known glasses that have thementioned features specified in Table 12.

The line corresponding to the formula y=0.269−0.12*x shown in FIG. 10provides a distinction between the Comparative Glasses having thefeatures specified in Table 12 and the Exemplary Glasses 1, 14, 21 and25. As can be seen in FIG. 10, the Exemplary Glasses (filled circles)and none of the Comparative Glasses (open circles) represented in FIG.10 fall above the line y=0.269−0.12*x, where y corresponds to(n_(d)−1)/d_(RT) and x corresponds to T_(i). In other words, some of theExemplary Glasses and none of the Comparative Glasses represented inFIG. 10 satisfy the following formula (IX)(a):

(n _(d)−1)/d _(RT)−(0.269−0.12*T _(i))>0.00  (IX)(a)

As can also be seen in FIG. 10, some of Exemplary Glasses and none ofthe Comparative Glasses represented in FIG. 10 fall above the liney=0.274−0.12*x, where y corresponds to (n_(d)−1)/d_(RT) and xcorresponds to T_(i). In other words, the Exemplary Glasses and none ofthe Comparative Glasses represented in FIG. 10 satisfy the followingformula (IX)(b):

(n _(d)−1)/d _(RT)−(0.274−0.12*T _(i))>0.00  (IX)(b)

TABLE 13 Attributes of Comparative Example Glasses Having the FeaturesSpecified in Tables 11 and 12 Ex. # C14 C15 C16 C17 C18 C19 C20 C21Composition B₂O₃ mol. % 37.09 31.89 20.87 22.20 15.37 15.37 39.37 16.45Nb₂O₅ mol. % 12.81 1.42 7.25 6.00 5.52 5.52 1.83 6.02 WO₃ mol. % 0 00.44 0 0 0 16.07 0 La₂O₃ mol. % 15.33 24.95 23.64 18.60 22.61 22.5820.39 21.76 Gd₂O₃ mol. % 0.90 15.68 3.15 4.80 4.90 4.94 0 4.65 Bi₂O₃mol. % 0 0 0 0 0 0 0 0 ZrO₂ mol. % 4.62 11.07 7.12 6.50 9.14 9.06 5.278.75 TeO₂ mol. % 0 0 0 0 0 0 0 0 SiO₂ mol. % 2.70 3.15 11.81 11.20 11.6311.63 0 12.61 Al₂O₃ mol. % 0.80 0 0 0 0 0 0 0 ThO₂ mol. % 0 0 0 0 0 0 00 GeO₂ mol. % 4.64 0 0 0 0 0 0 0 Ta₂O₅ mol. % 5.29 0 0 0 2.26 2.24 0.730 PbO mol. % 0 0 0 0 0 0 0 0 F mol. % 0 0 0 0 0 0 0 0 V₂O₅ mol. % 0 0 00 0 0 0 0 Cl mol. % 0 0 0 0 0 0 0 0 Br mol. % 0 0 0 0 0 0 0 0 I mol. % 00 0 0 0 0 0 0 RE₂O₃ + ZrO₂ + TiO₂ + Nb₂O₅ + WO₃ mol. % 49.48 64.95 65.1562.90 69.25 69.26 59.90 70.77 WO₃ + TiO₂ mol. % 15.82 11.82 23.62 27.0027.08 27.17 30.26 22.14 TiO₂ + Nb₂O₅ mol. % 28.63 13.25 30.43 33.0032.60 32.69 16.01 28.16 R₂O + RO mol. % 0 0 1.47 3.70 1.50 1.50 0 0Measured properties T_(i) 0.7961 0.4754 0.5292 0.528 0.5553 CompositionTiO₂ − SiO₂ mol. % 13.12 8.671 11.37 15.80 15.45 15.53 14.18 9.524B₂O₃ + SiO₂ − P₂O₅ mol. % 39.80 35.05 32.68 33.40 26.99 27.00 39.3729.06 Measured properties (n_(d) − 1)/d_(RT) cm³/g 0.1663 0.2041 0.19280.1928 0.1931 n_(d) 1.873 2.000 2.0451 2.0451 2.0233 (n_(d) − 1)/d_(RT)− (0.269 − 0.12 * T_(i)) −0.0072 −0.0079 −0.0127 −0.0128 (n_(d) −1)/d_(RT) − (0.274 − 0.12 *T_(i)) −0.0122 −0.0129 −0.0177 −0.0178Predicted and calculated properties P_(ref) 0.2147 0.1574 0.2035 0.20970.2028 0.2029 0.1796 0.199 P_(n) 1.9667 2.016 2.0259 1.9985 2.06642.0664 1.9297 2.0545 P_(ref) − (0.269 − 0.12 * T_(i)) −0.0037 −0.0161−0.0018 −0.0023 −0.0027 −0.0027 −0.0027 −0.0034 P_(ref) − (0.274 − 0.12*T_(i)) −0.0087 −0.0211 −0.0068 −0.0073 −0.0077 −0.0077 −0.0077 −0.0084Ex. # C22 C23 C24 C25 C26 C27 C28 Composition B₂O₃ mol. % 21.28 28.4138.96 20.44 24.70 28.50 19.82 Nb₂O₅ mol. % 5.36 7.19 5.10 5.94 4.30 4.003.50 WO₃ mol. % 0 3.44 0 0 0.20 0.20 4.50 La₂O₃ mol. % 22.51 21.70 16.6519.34 22.50 22.70 22.32 Gd₂O₃ mol. % 2.39 0 2.99 8.84 0 0 3.00 Bi₂O₃mol. % 0 6.02 0 0 0 0 0 ZrO₂ mol. % 7.29 7.15 7.41 7.08 7.00 6.00 6.61TeO₂ mol. % 0 0 0 0 0 0 0 SiO₂ mol. % 12.09 8.95 5.94 12.49 12.80 10.6011.81 Al₂O₃ mol. % 0 0 0 0 0 0 0 ThO₂ mol. % 0 0 0 0 0 0 0 GeO₂ mol. % 00 0 0 0 0 0 Ta₂O₅ mol. % 0 0.0079 0 0 0 0 0 PbO mol. % 0 0 0 0 0 0 0 Fmol. % 0 0 0 0 0 0 0 V₂O₅ mol. % 0 0 0 0 0 0 0 Cl mol. % 0 0 0 0 0 0 0Br mol. % 0 0 0 0 0 0 0 I mol. % 0 0 0 0 0 0 0 RE₂O₃ + ZrO₂ + TiO₂ +Nb₂O₅ + WO₃ mol. % 63.98 56.58 55.03 63.48 62.50 60.90 68.37 WO₃ + TiO₂mol. % 26.05 20.41 18.76 20.73 25.20 24.20 28.53 TiO₂ + Nb₂O₅ mol. %31.41 24.17 23.87 26.68 29.30 28.00 27.53 R₂O + RO mol. % 2.65 0.031 03.59 0 0 0 Measured properties T_(i) 0.5061 0.5313 0.5693 0.5034 0.50790.5696 Composition TiO₂ − SiO₂ mol. % 13.96 8.019 12.82 8.247 12.2013.40 12.21 B₂O₃ + SiO₂ − P₂O₅ mol. % 33.37 37.36 44.90 32.93 37.5039.10 31.63 Measured properties (n_(d) − 1)/d_(RT) cm³/g 0.1995 0.2020.1938 0.2042 0.200 0.1923 n_(d) 2.0034 1.923 1.9886 1.980 1.960 2.000(n_(d) − 1)/d_(RT) − (0.269 − 0.12 * T_(i)) −0.0088 −0.0033 −0.0068−0.0044 −0.0081 −0.0083 (n_(d) − 1)/d_(RT) − (0.274 − 0.12 * T_(i))−0.0138 −0.0083 −0.0118 −0.0094 −0.0131 −0.0133 Predicted and calculatedproperties P_(ref) 0.2046 0.1963 0.1995 0.1942 0.2043 0.2015 0.1959P_(n) 2.008 2.0229 1.9186 2.0218 1.9763 1.9644 2.018 P_(ref) − (0.269 −0.12 * T_(i)) −0.0037 −0.0041 −0.0057 −0.0065 −0.0043 −0.0066 −0.0048P_(ref) − (0.274 − 0.12 * T_(i)) −0.0087 −0.0091 −0.0107 −0.0115 −0.0093−0.0116 −0.0098

The Exemplary Examples represented in FIG. 10 are, according tomeasurement, superior in terms of combination of T; and (n_(d)−1)/d_(RT)to the best known Comparative Glasses that have the features specifiedin Table 12.

FIG. 11 is a plot showing the relationship between the density parameterP_(d) (Formula Ill) and the refractive index parameter P_(n) (FormulaII) for some of the Exemplary Glasses and some of the ComparativeGlasses. The Exemplary Glasses (filled circles) are the Examples 1 to 4,18 to 21, 29, 30, 52, 53, 63 to 75, 77 to 105, 107 to 124, 126, 127,130, 131 and 133 to 147 from Table 6. The Comparative Glasses (opencircles) are the Examples C29 to C38 from Table 7. All of the ExemplaryGlasses and Comparative Glasses shown in FIG. 11 have the featuresspecified in Table 14. In Table 14, the specification “Not limited”refers to a limitation that was not considered when selecting thecompositions.

TABLE 14 Limitations for glass compositions shown in FIG. 11 QuantityUnit Min Max WO₃ mol. % 1 40 ZrO₂ mol. % 0.3 20 B₂O₃ mol. % 0 40 La₂O₃mol. % 0 35 Bi₂O₃ mol. % 0 35 ZnO mol. % 0 35 Ta₂O₅ mol. % 0 25 Al₂O₃mol. % 0 10 ThO₂ mol. % 0 10 TeO₂ mol. % 0 10 V₂O₅ mol. % 0 5 RE₂O₃ +ZrO₂ + TiO₂ + Nb₂O₅ + mol. % 10 Not limited WO₃ TiO₂ + Nb₂O₅ mol. % 0 35SiO₂ + GeO₂ mol. % 0 4.8 B₂O₃ + SiO₂ − P₂O₅ mol. % 0.5 Not limitedP_(Tg) ° C. 500 700 P_(d) g/cm³ Not limited 6 P_(n) 0 Not limited

The above-enumerated Comparative Glasses were selected as having thehighest refractive index parameter P_(n) at comparable values of densityparameter P_(d) among the known glasses that have the features specifiedin Table 14.

The line corresponding to the formula y=1.571+0.083*x shown in FIG. 11provides a distinction between the Comparative Glasses having thefeatures specified in Table 14 and the Exemplary Glasses 1 to 4, 18 to21, 29, 30, 52, 53, 63 to 75, 77 to 105, 107 to 124, 126, 127, 130, 131and 133 to 147. As can be seen in FIG. 11, the Exemplary Glasses (filledcircles) and none of the Comparative Glasses (open circles) representedin FIG. 11 fall above the line y=1.571+0.083*x, where y corresponds tothe refractive index parameter P_(n) and x corresponds to the densityparameter P_(d). In other words, some of the Exemplary Glasses and noneof the Comparative Glasses represented in FIG. 11 satisfy the followingformula (X):

P _(n)−(1.571+0.083*P _(d))>0.00  (X)

This means that, under the conditions specified in Table 14 above, someof the Exemplary Glasses are, by prediction, superior in terms of thecombination of d_(RT) and n_(d) to the best known Comparative Glassesthat have the features specified in Table 14.

FIG. 12 is a plot showing the relationship between d_(RT) and n_(d) forsome of the Exemplary Glasses and some of the Comparative Glasses. TheExemplary Glasses (filled circles) are the Examples 1 from Table 6. TheComparative Glasses (open circles) are the Examples C3, C11, C35 and C38to C44 from Table 7. All of the Exemplary Glasses and ComparativeGlasses shown in FIG. 12 have the features specified in Table 15. InTable 15, the specification “Not limited” refers to a limitation thatwas not considered when selecting the compositions.

TABLE 15 Limitations for glass compositions shown in FIG. 12 QuantityUnit Min Max WO₃ mol. % 1 40 ZrO₂ mol. % 0.3 20 B₂O₃ mol. % 0 40 La₂O₃mol. % 0 35 Bi₂O₃ mol. % 0 35 ZnO mol. % 0 35 Ta₂O₅ mol. % 0 25 Al₂O₃mol. % 0 10 ThO₂ mol. % 0 10 TeO₂ mol. % 0 10 V₂O₅ mol. % 0 5 RE₂O₃ +ZrO₂ + TiO₂ + Nb₂O₅ + mol. % 10 Not limited WO₃ TiO₂ + Nb₂O₅ mol. % 0 35SiO₂ + GeO₂ mol. % 0 4.8 B₂O₃ + SiO₂ − P₂O₅ mol. % 0.5 Not limited T_(g)° C. 500 700 d_(RT) g/cm³ Not limited 6 n_(d) 0 Not limited

The above-enumerated Comparative Glasses were selected as having thehighest measured values of n_(d) at comparable values of d_(RT) amongthe known glasses that have the mentioned features specified in Table15.

The line corresponding to the formula y=1.571+0.083*x shown in FIG. 12provides a distinction between the Comparative Glasses having thefeatures specified in Table 15 and the Exemplary Glasses. As can be seenin FIG. 12, the mentioned Exemplary Glasses (filled circles) and none ofthe Comparative Glasses (open circles) represented in FIG. 12 fall abovethe line y=1.571+0.083*x, where y corresponds to n_(d) and x correspondsto d_(RT). In other words, some of the Exemplary Glasses and none of theComparative Glasses represented in FIG. 12 satisfy the following formula(XI):

n _(d)−(1.571+0.083*d _(RT))>0.00  (XI)

This means that, under the conditions specified in Table 15 above, someof the Exemplary Glasses are, according to measurement, superior interms of combination of d_(RT) and n_(d) to the best known ComparativeGlasses that have the features specified in Table 15.

TABLE 16 Attributes of Comparative Example Glasses Having the FeaturesSpecified in Tables 14 and 15 Ex. # C3 C11 C29 C30 C31 C32 C33 C34Composition ZrO₂ mol. % 3.33 3.49 5.42 13.61 6.20 9.03 6.07 4.32 B₂O₃mol. % 23.24 24.73 38.44 27.33 33.65 39.84 38.93 30.61 La₂O₃ mol. %13.29 14.43 12.26 27.23 24.58 15.52 17.17 20.17 Bi₂O₃ mol. % 0 0 0 0 0 00 0 ZnO mol. % 28.23 27.73 21.38 0 0 15.08 0 0 Ta₂O₅ mol. % 3.33 3.861.05 13.61 8.91 0 6.06 4.42 Al₂O₃ mol. % 0 0 0 0 0 0 0 0 ThO₂ mol. % 0 00 0 0 0 0 0 TeO₂ mol. % 0 0 0 0 0 0 0 0 V₂O₅ mol. % 0 0 0 0 0 0 0 0RE₂O₃ + ZrO₂ + TiO₂ + mol. % 41.89 42.06 38.01 59.06 57.38 45.07 55.0143.88 Nb₂O₅ + WO₃ TiO₂ + Nb₂O₅ mol. % 11.17 10.21 15.59 0 8.32 17.0020.08 15.56 SiO₂ + GeO₂ mol. % 3.33 1.62 1.11 0 0 0 0 0 B₂O₃ + SiO₂ −P₂O₅ mol. % 26.56 26.35 39.55 27.33 33.65 39.84 38.93 30.61 Measuredproperties d_(RT) g/cm³ 5.400 5.480 5.940 n_(d) 1.968 1.968 1.953 T_(g)° C. 591.0 592.0 679.0 n_(d) − (1.571 + 0.083 * d_(RT)) −0.0512 −0.0578−0.111 Predicted and calculated properties P_(d) 5.3451 5.3993 4.60275.9748 5.7317 4.8154 4.6556 4.9478 P_(n) 1.9723 1.9714 1.893 2.04222.0396 1.9557 1.9303 1.9566 P_(Tg) 585.0 585.9 612.4 687.3 682.1 629.9659.6 683.1 P_(n) − (1.571 + 0.083 * P_(d)) −0.0424 −0.0478 −0.0601−0.0247 −0.0072 −0.0150 −0.0272 −0.0251 Ex. # C35 C36 C37 C38 C39 C40C41 C42 Composition ZrO₂ mol. % 6.07 15.74 6.08 3.64 10.17 3.23 3.653.67 B₂O₃ mol. % 30.21 39.36 23.61 31.51 39.44 22.59 31.62 31.75 La₂O₃mol. % 15.65 15.74 13.25 12.30 9.70 12.92 12.35 12.41 Bi₂O₃ mol. % 0 0 00 0 0 0 0 ZnO mol. % 15.36 4.66 26.13 31.02 12.80 27.44 33.52 31.27Ta₂O₅ mol. % 0 0.51 7.28 2.07 0 3.23 2.47 3.66 Al₂O₃ mol. % 0 0 0 0 0 00 0 ThO₂ mol. % 0 0 0 0 0 0 0 0 TeO₂ mol. % 0 0 0 0 0 0 0 0 V₂O₅ mol. %0 0 0 0 0 0 0 0 RE₂O₃ + ZrO₂ + TiO₂ + mol. % 48.52 50.95 40.06 31.7439.24 43.50 28.73 29.63 Nb₂O₅ + WO₃ TiO₂ + Nb₂O₅ mol. % 25.20 10.74 8.2913.76 10.37 13.63 11.47 11.50 SiO₂ + GeO₂ mol. % 4.15 4.52 2.92 3.654.32 3.23 3.66 3.68 B₂O₃ + SiO₂ − P₂O₅ mol. % 34.36 43.88 26.53 35.1643.75 25.83 35.28 35.43 Measured properties d_(RT) g/cm³ 4.650 5.4504.820 4.230 5.370 4.850 4.930 n_(d) 1.9468 1.958 1.920 1.860 1.9701.9107 1.9171 T_(g) ° C. 623.0 598.0 590.0 597.0 591.0 588.0 593.0 n_(d)− (1.571 + 0.083 * d_(RT)) −0.0102 −0.0654 −0.0511 −0.0621 −0.0467−0.0629 −0.0631 Predicted and calculated properties P_(d) 4.6099 4.75355.3396 4.8324 4.5885 5.2501 4.8686 4.8526 P_(n) 1.9193 1.9228 1.97431.9197 1.8412 1.9632 1.9139 1.9172 P_(Tg) 651.7 679.4 589.5 587.3 606.7590.2 581.9 585.1 P_(n) − (1.571 + 0.083 * P_(d)) −0.0343 −0.0428−0.0399 −0.0524 −0.1107 −0.0435 −0.0612 −0.0566 Ex. # C43 C44Composition ZrO₂ mol. % 3.64 4.43 B₂O₃ mol. % 31.13 31.52 La₂O₃ mol. %12.31 12.31 Bi₂O₃ mol. % 0 0 ZnO mol. % 32.60 32.60 Ta₂O₅ mol. % 3.633.63 Al₂O₃ mol. % 0 0 ThO₂ mol. % 0 0 TeO₂ mol. % 0 0 V₂O₅ mol. % 0 0RE₂O₃ + ZrO₂ + TiO₂ + mol. % 28.22 28.62 Nb₂O₅ + WO₃ TiO₂ + Nb₂O₅ mol. %11.02 10.63 SiO₂ + GeO₂ mol. % 3.64 3.63 B₂O₃ + SiO₂ − P₂O₅ mol. % 34.7735.15 Measured properties d_(RT) g/cm³ 4.930 4.920 n_(d) 1.9126 1.9114T_(g) ° C. 590.0 592.0 n_(d) − (1.571 + 0.083 * d_(RT)) −0.0676 −0.068Predicted and calculated properties P_(d) 4.8591 4.8562 P_(n) 1.91381.9109 P_(Tg) 584.2 584.4 P_(n) − (1.571 + 0.083 * P_(d)) −0.0605−0.0631

FIG. 13 shows the total transmittance T of Exemplary Glass 1 accordingto the present disclosure at wavelengths of from 350 nm to about 500 nm.Before testing, the sample was bleached at 650° C. for 90 hours. Beforebleaching, the glass was heated from the room temperature with the rateof about 4° C./min. After bleaching, the glass was cooled to the roomtemperature with the rate from about 2° C./min. The total transmittanceT data shown in FIG. 13 was obtained from glass sample having athickness of 10 mm. As can be seen in FIG. 13, the Exemplary Glass 1provides a total transmittance T=70% at the wavelength k=439 nm.

The following non-limiting aspects are encompassed by the presentdisclosure. To the extent not already described, any one of the featuresof the first through the eighty-sixth aspect may be combined in part orin whole with features of any one or more of the other aspects of thepresent disclosure to form additional aspects, even if such acombination is not explicitly described.

According to a first aspect, the glass comprises a plurality ofcomponents, the glass having a composition of the components comprisinggreater than or equal to 3.0 mol. % and less than or equal to 35.0 mol.% WO₃, greater than or equal to 0.3 mol. % and less than or equal to50.0 mol. % TiO₂, greater than or equal to 0.3 mol. % and less than orequal to 50.0 mol. % Nb₂O₅, greater than or equal to 0.0 mol. % and lessthan or equal to 20.0 mol. % Bi₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % TeO₂, greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. % PbO, greater than or equalto 0.0 mol. % and less than or equal to 3.0 mol. % MoO₃, greater than orequal to 0.0 mol. % and less than or equal to 1.0 mol. % V₂O₅, greaterthan or equal to 0.0 at. % and less than or equal to 5.0 at. % F,greater than or equal to 0.0 at. % and less than or equal to 1.0 at. %Cl, greater than or equal to 0.0 at. % and less than or equal to 1.0 at.% Br, greater than or equal to 0.0 at. % and less than or equal to 1.0at. % I, greater than or equal to 0.6 mol. % and less than or equal to60.0 mol. % TiO₂+Nb₂O₅ and may optionally contain one or more componentsselected from Al₂O₃, B₂O₃, BaO, CaO, Gd₂O₃, GeO₂, K₂O, La₂O₃, Li₂O, MgO,Na₂O, P₂O₅, SiO₂, SrO, Ta₂O₅, Y₂O₃, Yb₂O₃, ZnO and ZrO₂, wherein theglass has liquidus temperature, T_(liq), that is greater than or equalto 850° C. and less than or equal to 1350° C., and the glass satisfiesthe conditions: 1.92≤P_(n)≤2.08 and P_(n)−(1.437+0.0005*T_(liq))>0.00,where P_(n) is a refractive index parameter, calculated from the glasscomposition in terms of mol. % of the components according to theFormula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

where a symbol “*” means multiplication.

According to a second aspect, the glass of the first aspect, wherein theglass has a refractive index at 587.56 nm, n_(d), that is greater thanor equal to 1.92 and less than or equal to 2.08 and wherein the glasssatisfies the condition: n_(d)−(1.437+0.0005*T_(liq))>0.00.

According to a third aspect, the glass of any one of aspects 1-2,wherein the glass satisfies the condition:n_(d)−(1.481+0.0005*T_(liq))>0.00, where n_(d) is refractive index at587.56 nm.

According to a fourth aspect, the glass of any one of aspects 1-3,wherein the glass satisfies the condition:P_(n)−(1.481+0.0005*T_(liq))>0.00.

According to a fifth aspect, the glass of any one of aspects 1-4,wherein the composition of the components comprises greater than orequal to 0.3 mol. % and less than or equal to 20.0 mol. % ZrO₂, greaterthan or equal to 0.0 mol. % and less than or equal to 25.0 mol. % ZnO,greater than or equal to 0.0 mol. % and less than or equal to 10.0 mol.% P₂O₅, greater than or equal to 0.0 mol. % and less than or equal to5.0 mol. % GeO₂, greater than or equal to 17.0 mol. % TiO₂+Nb₂O₅+ZrO₂and wherein the composition of the components satisfies the condition:0≤B₂O₃+SiO₂−P₂O₅[mol. %] 40.

According to a sixth aspect, the glass of any one of aspects 1-5,wherein the composition of the components comprises greater than orequal to 1.0 mol. % and less than or equal to 19.0 mol. % Nb₂O₅ andgreater than or equal to 1.0 mol. % and less than or equal to 19.0 mol.% TiO₂.

According to a seventh aspect, the glass of any one of aspects 1-6,wherein the composition of the components comprises greater than orequal to 5.0 mol. % La₂O₃, greater than or equal to 5.0 mol. % Nb₂O₅ andgreater than or equal to 5.0 mol. % TiO₂.

According to an eighth aspect, the glass of any one of aspects 1-7,wherein the composition of the components comprises greater than orequal to 6.0 mol. % WO₃, greater than or equal to 0.0 mol. % and lessthan or equal to 5.0 mol. % P₂O₅, greater than or equal to 95.0 mol. %R_(m)O_(n) and greater than or equal to 0.0 mol. % and less than orequal to 30.0 mol. % Al₂O₃+RE_(m)O_(n), where RE_(m)O_(n) is a total sumof rare earth metal oxides, and R_(m)O_(n) is a total sum of all oxides.

According to a ninth aspect, the glass of any one of aspects 1-8,wherein the composition of the components comprises greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO, whereR₂O is a total sum of monovalent metal oxides, and RO is a total sum ofdivalent metal oxides.

According to a tenth aspect, the glass of the ninth aspect, wherein thecomposition of the components comprises greater than or equal to 0.0mol. % and less than or equal to 1.0 mol. % R₂O+RO.

According to an eleventh aspect, the glass of any one of aspects 1-10,wherein the composition of the components comprises greater than orequal to 0.0 mol. % and less than or equal to 4.5 mol. % SiO₂.

According to a twelfth aspect, the glass of any one of aspects 1-11,wherein the composition of the components comprises greater than orequal to 10.0 mol. % and less than or equal to 40.0 mol. % B₂O₃, greaterthan or equal to 10.0 mol. % and less than or equal to 25.0 mol. %La₂O₃, greater than or equal to 3.0 mol. % and less than or equal to30.0 mol. % WO₃, greater than or equal to 0.3 mol. % and less than orequal to 30.0 mol. % TiO₂, greater than or equal to 0.3 mol. % and lessthan or equal to 20.0 mol. % Nb₂O₅, greater than or equal to 0.0 mol. %and less than or equal to 15.0 mol. % SiO₂, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % Bi₂O₃, greater than orequal to 0.0 mol. % and less than or equal to 10.0 mol. % Y₂O₃, greaterthan or equal to 0.0 mol. % and less than or equal to 10.0 mol. % ZrO₂,greater than or equal to 0.0 mol. % and less than or equal to 7.5 mol. %CaO, greater than or equal to 0.0 mol. % and less than or equal to 5.0mol. % BaO, greater than or equal to 0.0 mol. % and less than or equalto 4.0 mol. % Li₂O, greater than or equal to 0.0 mol. % and less than orequal to 4.0 mol. % SrO, greater than or equal to 0.0 mol. % and lessthan or equal to 3.0 mol. % Na₂O and greater than or equal to 0.0 mol. %and less than or equal to 2.0 mol. % K₂O.

According to a thirteenth aspect, the glass of any one of aspects 1-12,wherein the composition of the components comprises greater than orequal to 21.5 mol. % and less than or equal to 34.5 mol. % B₂O₃, greaterthan or equal to 13.0 mol. % and less than or equal to 24.0 mol. %La₂O₃, greater than or equal to 6.0 mol. % and less than or equal to22.0 mol. % TiO₂, greater than or equal to 4.5 mol. % and less than orequal to 18.0 mol. % Nb₂O₅, greater than or equal to 3.0 mol. % and lessthan or equal to 26.0 mol. % WO₃, greater than or equal to 0.5 mol. %and less than or equal to 8.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 12.5 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.5 mol. % Bi₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 6.5 mol. % Y₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 5.5 mol. %CaO, greater than or equal to 0.0 mol. % and less than or equal to 4.6mol. % BaO, greater than or equal to 0.0 mol. % and less than or equalto 3.6 mol. % Li₂O, greater than or equal to 0.0 mol. % and less than orequal to 3.6 mol. % SrO, greater than or equal to 0.0 mol. % and lessthan or equal to 2.7 mol. % Na₂O and greater than or equal to 0.0 mol. %and less than or equal to 1.8 mol. % K₂O.

According to a fourteenth aspect, the glass of any one of aspects 1-13,wherein the composition of the components comprises greater than orequal to 23.0 mol. % and less than or equal to 33.0 mol. % B₂O₃, greaterthan or equal to 14.5 mol. % and less than or equal to 22.5 mol. %La₂O₃, greater than or equal to 8.0 mol. % and less than or equal to20.0 mol. % TiO₂, greater than or equal to 6.0 mol. % and less than orequal to 16.5 mol. % Nb₂O₅, greater than or equal to 5.0 mol. % and lessthan or equal to 23.0 mol. % WO₃, greater than or equal to 1.75 mol. %and less than or equal to 7.25 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 11.5 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.0 mol. % Bi₂O₃, greater thanor equal to 0 mol. % and less than or equal to 5.75 mol. % Y₂O₃, greaterthan or equal to 0 mol. % and less than or equal to 4.75 mol. % CaO,greater than or equal to 0.0 mol. % and less than or equal to 4.0 mol. %BaO, greater than or equal to 0.0 mol. % and less than or equal to 3.2mol. % Li₂O, greater than or equal to 0.0 mol. % and less than or equalto 3.2 mol. % SrO, greater than or equal to 0.0 mol. % and less than orequal to 2.4 mol. % Na₂O and greater than or equal to 0.0 mol. % andless than or equal to 1.6 mol. % K₂O.

According to a fifteenth aspect, the glass of any one of aspects 1-14,wherein the composition of the components is substantially free of ZnO.

According to a sixteenth aspect, the glass of any one of aspects 1-15,wherein the composition of the components comprises greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % Y₂O₃, greaterthan or equal to 0.0 mol. % and less than or equal to 2.0 mol. % Ta₂O₅,greater than or equal to 0.0 mol. % and less than or equal to 2.0 mol. %TeO₂, greater than or equal to 0.0 mol. % and less than or equal to 0.5mol. % GeO₂, greater than or equal to 0.0 mol. % and less than or equalto 0.5 mol. % PbO, greater than or equal to 0.0 mol. % and less than orequal to 0.2 mol. % As₂O₃ and greater than or equal to 0.0 mol. % andless than or equal to 0.2 mol. % Sb₂O₃, and wherein the composition ofthe components is substantially free of fluorine and substantially freeof V₂O₅.

According to a seventeenth aspect, the glass of any one of aspects 1-16,wherein the glass satisfies the condition: T_(i)≥0.52, where T_(i) is atransmittance index, calculated from the glass composition in terms ofmol. % of the components according to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to an eighteenth aspect, the glass of the seventeenth aspect,wherein T_(i)≥0.57.

According to a nineteenth aspect, the glass of the eighteenth aspect,wherein 0.62≤T_(i)≤0.95.

According to a twentieth aspect, the glass of any one of aspects 1-19,wherein the glass satisfies the conditions: 4.5≤P_(d)≤5.5 and1.95≤P_(n)≤2.07, where P_(n) is a refractive index parameter, calculatedfrom the glass composition in terms of mol. % of the componentsaccording to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(d) is a density parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (III):

P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)

wherein a symbol “*” means multiplication.

According to a twenty-first aspect, the glass of any one of aspects1-20, wherein the glass has a density at room temperature, d_(RT), thatis greater than or equal to 4.5 g/cm³ and less than or equal to 5.5g/cm³ and a refractive index at 587.56 nm, n_(d), that is greater thanor equal to 1.95 and less than or equal to 2.07.

According to a twenty-second aspect, the glass of any one of aspects1-21, wherein the liquidus temperature, T_(liq), is less than or equalto 1100° C.

According to a twenty-third aspect, the glass of the twenty-secondaspect, wherein the liquidus temperature, T_(liq), is less than or equalto 1050° C.

According to a twenty-fourth aspect, the glass of any one of aspects1-23, wherein the glass has a decimal logarithm of liquidus viscosity,Log(η_(liq) [P]), that is greater than or equal to 0.50.

According to a twenty-fifth aspect, the glass of the twenty-fourthaspect, wherein the decimal logarithm of liquidus viscosity, Log(η_(liq)[P]), is greater than or equal to 0.75.

According to a twenty-sixth aspect, a glass of any one of aspects 1-25,wherein when cooled in air from 1100° C. to 500° C. in 2.5 minutes, theglass does not crystallize.

According to a twenty-seventh aspect, a glass of any one of aspects1-26, wherein when having a thickness of 10 mm, the glass can bebleached in less than or equal to 96 hours at a temperature less than orequal to 700° C.

According to a twenty-eighth aspect, a method for manufacturing anoptical element, the method comprising processing the glass of any oneof aspects 1-27.

According to a twenty-ninth aspect, an optical element comprising theglass of any one of aspects 1-28.

According to a thirtieth aspect, the glass comprises a plurality ofcomponents, the glass having a composition of the components comprisinggreater than or equal to 7.5 mol. % and less than or equal to 28.0 mol.% TiO₂, greater than or equal to 1.0 mol. % and less than or equal to40.0 mol. % B₂O₃, greater than or equal to 0.3 mol. % and less than orequal to 19.5 mol. % Nb₂O₅, greater than or equal to 0.0 mol. % and lessthan or equal to 35.0 mol. % WO₃, greater than or equal to 0.0 mol. %and less than or equal to 25.0 mol. % La₂O₃, greater than or equal to0.0 mol. % and less than or equal to 25.0 mol. % Gd₂O₃, greater than orequal to 0.0 mol. % and less than or equal to 20.0 mol. % Bi₂O₃, greaterthan or equal to 0.0 mol. % and less than or equal to 20.0 mol. % ZrO₂,greater than or equal to 0.0 mol. % and less than or equal to 20.0 mol.% TeO₂, greater than or equal to 0.0 mol. % and less than or equal to13.5 mol. % SiO₂, greater than or equal to 0.0 mol. % and less than orequal to 10.0 mol. % Al₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % ThO₂, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % GeO₂, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % Ta₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % PbO, greaterthan or equal to 0.0 mol. % and less than or equal to 1.0 mol. % V₂O₅,greater than or equal to 0.0 at. % and less than or equal to 5.0 at. %F, greater than or equal to 0.0 at. % and less than or equal to 1.0 at.% Cl, greater than or equal to 0.0 at. % and less than or equal to 1.0at. % Br, greater than or equal to 0.0 at. % and less than or equal to1.0 at. % I, greater than or equal to 10.0 mol. %RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, less than or equal to 40.0 mol. % WO₃+TiO₂,less than or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than or equal to0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO and mayoptionally contain P₂O₅, wherein the composition of the componentssatisfies the conditions: TiO₂−SiO₂[mol. %]≥7.5 and B₂O₃+SiO₂−P₂O₅[mol.%]≥0.00, and the glass satisfies the conditions: 1.9≤P_(n)≤2.1 andP_(ref)−(0.269−0.12*T_(i))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(ref) is a refraction parameter, calculated from the glass compositionin terms of mol. % of the components according to the Formula (IV):

P_(ref)(cm³/g)=0.000087034*SiO₂−0.00012035*B₂O₃−0.0012566*La₂O₃+0.0011411*TiO₂−0.00031654*ZnO+0.000088066*CaO+0.0020444*Nb₂O₅−0.00023383*MgO−0.00086501*BaO−0.0004486*WO₃−0.0014114*Gd₂O₃−0.00023872*Y₂O₃−0.00031575*Ta₂O₅+0.00011894*Li₂O+0.00027178*Al₂O₃−0.000099802*Na₂O−0.00028391*GeO₂−0.00030531*SrO−0.00072061*Bi₂O₃−0.0010964*Yb₂O₃+0.00022839*K₂O−0.00086617*PbO+0.00027129*TeO₂+0.198,  (IV)

where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, R₂O is a total sum of monovalent metal oxides, RO is a totalsum of divalent metal oxides, and an asterisk (*) means multiplication.

According to a thirty-first aspect, the glass of the thirtieth aspect,wherein the glass has a refractive index at 587.56 nm, n_(d), that isgreater than or equal to 1.9 and less than or equal to 2.1 and whereinthe glass satisfies the condition:(n_(d)−1)/d_(RT)−(0.269−0.12*T_(i))>0.00, where d_(RT) (g/cm³) is adensity at room temperature, T_(i) is a transmittance index, calculatedfrom the glass composition in terms of mol. % of the componentsaccording to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to a thirty-second aspect, the glass of any one of aspects30-31, wherein the glass satisfies the condition:(n_(d)−1)/d_(RT)−(0.274−0.12*T_(i))>0.00, where n_(d) is a refractiveindex at 587.56 nm, d_(RT) (g/cm³) is a density at room temperature, andT_(i) is a transmittance index, calculated from the glass composition interms of mol. % of the components according to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to a thirty-third aspect, the glass of any one of aspects30-32, wherein the glass satisfies the condition:P_(ref)−(0.274−0.12*T_(i))>0.00, where T_(i) is a transmittance index,calculated from the glass composition in terms of mol. % of thecomponents according to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to a thirty-fourth aspect, the glass of any one of aspects30-33, wherein the composition of the components comprises greater thanor equal to 7.5 mol. % and less than or equal to 19.0 mol. % TiO₂ andgreater than or equal to 1.0 mol. % and less than or equal to 19.0 mol.% Nb₂O₅.

According to a thirty-fifth aspect, the glass of any one of aspects30-34, wherein the composition of the components comprises greater thanor equal to 5.0 mol. % La₂O₃ and greater than or equal to 5.0 mol. %Nb₂O₅.

According to a thirty-sixth aspect, the glass of any one of aspects30-35, wherein the composition of the components comprises greater thanor equal to 6.0 mol. % WO₃, greater than or equal to 0.0 mol. % and lessthan or equal to 5.0 mol. % P₂O₅, greater than or equal to 95.0 mol. %R_(m)O_(n) and greater than or equal to 0.0 mol. % and less than orequal to 30.0 mol. % Al₂O₃+RE_(m)O_(n), where RE_(m)O_(n) is a total sumof rare earth metal oxides, and R_(m)O_(n) is a total sum of all oxides.

According to a thirty-seventh aspect, the glass of any one of aspects30-36, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO.

According to a thirty-eighth aspect, the glass of the thirty-seventhaspect, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 1.0 mol. % R₂O+RO.

According to a thirty-ninth aspect, the glass of any one of aspects30-38, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 4.5 mol. % SiO₂.

According to a fortieth aspect, the glass of any one of aspects 30-39,wherein the composition of the components comprises greater than orequal to 10.0 mol. % and less than or equal to 40.0 mol. % B₂O₃, greaterthan or equal to 10.0 mol. % and less than or equal to 25.0 mol. %La₂O₃, greater than or equal to 0.0 mol. % and less than or equal to30.0 mol. % WO₃, greater than or equal to 0.0 mol. % and less than orequal to 10.0 mol. % Bi₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % Y₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 7.5 mol. % CaO, greater than or equalto 0.0 mol. % and less than or equal to 5.0 mol. % BaO, greater than orequal to 0.0 mol. % and less than or equal to 4.0 mol. % Li₂O, greaterthan or equal to 0.0 mol. % and less than or equal to 4.0 mol. % SrO,greater than or equal to 0.0 mol. % and less than or equal to 3.0 mol. %Na₂O and greater than or equal to 0.0 mol. % and less than or equal to2.0 mol. % K₂O.

According to a forty-first aspect, the glass of any one of aspects30-40, wherein the composition of the components comprises greater thanor equal to 21.5 mol. % and less than or equal to 34.5 mol. % B₂O₃,greater than or equal to 13.0 mol. % and less than or equal to 24.0 mol.% La₂O₃, greater than or equal to 7.5 mol. % and less than or equal to22.0 mol. % TiO₂, greater than or equal to 4.5 mol. % and less than orequal to 18.0 mol. % Nb₂O₅, greater than or equal to 2.0 mol. % and lessthan or equal to 26.0 mol. % WO₃, greater than or equal to 0.5 mol. %and less than or equal to 8.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 12.5 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.5 mol. % Bi₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 6.5 mol. % Y₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 5.5 mol. %CaO, greater than or equal to 0.0 mol. % and less than or equal to 4.6mol. % BaO, greater than or equal to 0.0 mol. % and less than or equalto 3.6 mol. % Li₂O, greater than or equal to 0.0 mol. % and less than orequal to 3.6 mol. % SrO, greater than or equal to 0.0 mol. % and lessthan or equal to 2.7 mol. % Na₂O and greater than or equal to 0.0 mol. %and less than or equal to 1.8 mol. % K₂O.

According to a forty-second aspect, the glass of any one of aspects30-37, wherein the composition of the components comprises greater thanor equal to 23.0 mol. % and less than or equal to 33.0 mol. % B₂O₃,greater than or equal to 14.5 mol. % and less than or equal to 22.5 mol.% La₂O₃, greater than or equal to 8.0 mol. % and less than or equal to20.0 mol. % TiO₂, greater than or equal to 6.0 mol. % and less than orequal to 16.5 mol. % Nb₂O₅, greater than or equal to 5.0 mol. % and lessthan or equal to 23.0 mol. % WO₃, greater than or equal to 1.75 mol. %and less than or equal to 7.25 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 11.5 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.0 mol. % Bi₂O₃, greater thanor equal to 0 mol. % and less than or equal to 5.75 mol. % Y₂O₃, greaterthan or equal to 0 mol. % and less than or equal to 4.75 mol. % CaO,greater than or equal to 0.0 mol. % and less than or equal to 4.0 mol. %BaO, greater than or equal to 0.0 mol. % and less than or equal to 3.2mol. % Li₂O, greater than or equal to 0.0 mol. % and less than or equalto 3.2 mol. % SrO, greater than or equal to 0.0 mol. % and less than orequal to 2.4 mol. % Na₂O and greater than or equal to 0.0 mol. % andless than or equal to 1.6 mol. % K₂O.

According to a forty-third aspect, the glass of any one of aspects30-42, wherein the composition of the components is substantially freeof ZnO.

According to a forty-fourth aspect, the glass of any one of aspects30-43, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 5.0 mol. % Y₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 2.0 mol. %Ta₂O₅, greater than or equal to 0.0 mol. % and less than or equal to 2.0mol. % TeO₂, greater than or equal to 0.0 mol. % and less than or equalto 0.5 mol. % GeO₂, greater than or equal to 0.0 mol. % and less than orequal to 0.5 mol. % PbO, greater than or equal to 0.0 mol. % and lessthan or equal to 0.2 mol. % As₂O₃ and greater than or equal to 0.0 mol.% and less than or equal to 0.2 mol. % Sb₂O₃, and wherein thecomposition of the components is substantially free of fluorine andsubstantially free of V₂O₅.

According to a forty-fifth aspect, the glass of any one of aspects30-44, wherein the glass satisfies the condition: T_(i)≥0.52, whereT_(i) is a transmittance index, calculated from the glass composition interms of mol. % of the components according to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to a forty-sixth aspect, the glass of the forty-fifth aspect,wherein T_(i)≥0.57.

According to a forty-seventh aspect, the glass of the forty-sixthaspect, wherein 0.62≤T_(i)≤0.95.

According to a forty-eighth aspect, the glass of any one of aspects30-47, wherein the glass satisfies the conditions: 4.5≤P_(d)≤5.5 and1.95≤P_(n)≤2.07, where P_(d) is a density parameter, calculated from theglass composition in terms of mol. % of the components according to theFormula (III):

P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂  (III).

According to a fourth-ninth aspect, the glass of any one of aspects30-48, wherein the glass has a density at room temperature, d_(RT), thatis greater than or equal to 4.5 g/cm³ and less than or equal to 5.5g/cm³ and a refractive index at 587.56 nm, n_(d), that is greater thanor equal to 1.95 and less than or equal to 2.07.

According to a fiftieth aspect, the glass of any one of aspects 30-49,wherein the glass has a liquidus temperature, T_(liq), that is less thanor equal to 1100° C.

According to a fifty-first aspect, the glass of the fifty-second aspect,wherein the liquidus temperature, T_(liq), is less than or equal to1050° C.

According to a fifty-second aspect, the glass of any one of aspects30-51, wherein the glass has a decimal logarithm of liquidus viscosity,Log(η_(liq) [P]), that is greater than or equal to 0.50.

According to a fifty-third aspect, the glass of the fifty-fourth aspect,wherein the decimal logarithm of liquidus viscosity, Log(η_(liq) [P]),is greater than or equal to 0.75.

According to a fifty-fourth aspect, a glass of any one of aspects 30-53,wherein when cooled in air from 1100° C. to 500° C. in 2.5 minutes, theglass does not crystallize.

According to a fifty-fifth aspect, a glass of any one of aspects 30-54,wherein when having a thickness of 10 mm, the glass can be bleached inless than or equal to 96 hours at a temperature less than or equal to700° C.

According to a fifty-sixth aspect, a method for manufacturing an opticalelement, the method comprising processing the glass of any one ofaspects 30-55.

According to a fifty-seventh aspect, an optical element comprising theglass of any one of aspects 30-56.

According to a fifty-eighth aspect, the glass comprises a plurality ofcomponents, the glass having a composition of the components comprisinggreater than or equal to 1.0 mol. % and less than or equal to 40.0 mol.% WO₃, greater than or equal to 0.3 mol. % and less than or equal to20.0 mol. % ZrO₂, greater than or equal to 0.0 mol. % and less than orequal to 40.0 mol. % B₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 35.0 mol. % La₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 35.0 mol. % Bi₂O₃, greater than or equal to0.0 mol. % and less than or equal to 35.0 mol. % ZnO, greater than orequal to 0.0 mol. % and less than or equal to 25.0 mol. % Ta₂O₅, greaterthan or equal to 0.0 mol. % and less than or equal to 10.0 mol. % Al₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 10.0 mol.% ThO₂, greater than or equal to 0.0 mol. % and less than or equal to10.0 mol. % TeO₂, greater than or equal to 0.0 mol. % and less than orequal to 5.0 mol. % V₂O₅, greater than or equal to 10.0 mol. %RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, greater than or equal to 0.0 mol. % and lessthan or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than or equal to 0.0mol. % and less than or equal to 4.8 mol. % SiO₂+GeO₂ and may optionallycontain one or more components selected from P₂O₅, BaO, CaO, K₂O, Li₂O,MgO, Na₂O, PbO and SrO, wherein the composition of the componentssatisfies the condition: B₂O₃+SiO₂−P₂O₅[mol. %]≥0.50, and the glasssatisfies the conditions: 500≤P_(Tg)≤700, P_(d)<6.0 andP_(n)−(1.571+0.083*P_(d))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):

P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)

P_(d) is a density parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (III):

P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)

P_(Tg) is a T_(g) parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (V):

P _(Tg)(°C.)=595.358−0.63217*B₂O₃−0.46552*SiO₂+1.1849*TiO₂+0.59610*Nb₂O₅−1.6293*WO₃+1.3877*ZrO₂+4.4090*La₂O₃+4.1695*Y₂O₃−5.0756*Bi₂O₃+0.55630*CaO−5.3892*PbO−4.2774*TeO₂+1.8497*Al₂O₃−0.40659*GeO₂−1.7011*ZnO−4.1520*Li₂O+3.0777*Gd₂O₃,  (V)

where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, and an asterisk (*) means multiplication.

According to a fifty-ninth aspect, the glass of the fifty-eighth aspect,wherein the glass has a glass transition temperature, T_(g), that isgreater than or equal to 500° C. and less than or equal to 700° C. and adensity at room temperature, d_(RT), that is less than or equal to 6.0g/cm³ and wherein the glass satisfies the following condition:n_(d)−(1.571+0.083*d_(RT))>0.00, where n_(d) is a refractive index at587.56 nm.

According to a sixtieth aspect, the glass of any one of aspects 58-59,wherein the composition of the components comprises greater than orequal to 1.0 mol. % and less than or equal to 19.0 mol. % Nb₂O₅ andgreater than or equal to 1.0 mol. % and less than or equal to 19.0 mol.% TiO₂.

According to a sixty-first aspect, the glass of any one of aspects58-60, wherein the composition of the components comprises greater thanor equal to 5.0 mol. % La₂O₃, greater than or equal to 5.0 mol. % Nb₂O₅and greater than or equal to 5.0 mol. % TiO₂.

According to a sixty-second aspect, the glass of any one of aspects58-61, wherein the composition of the components comprises greater thanor equal to 6.0 mol. % WO₃, greater than or equal to 0.0 mol. % and lessthan or equal to 20.0 mol. % Bi₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 5.0 mol. % P₂O₅, greater than or equal to 95.0mol. % R_(m)O_(n) and greater than or equal to 0.0 mol. % and less thanor equal to 30.0 mol. % Al₂O₃+RE_(m)O_(n), where RE_(m)O_(n) is a totalsum of rare earth metal oxides, and R_(m)O_(n) is a total sum of alloxides.

According to a sixty-third aspect, the glass of any one of aspects58-62, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO,where R₂O is a total sum of monovalent metal oxides, and RO is a totalsum of divalent metal oxides.

According to a sixty-fourth aspect, the glass of the sixty-third aspect,wherein the glass further comprises greater than or equal to 0.0 mol. %and less than or equal to 1.0 mol. % R₂O+RO, where R₂O is total sum ofmonovalent metal oxides, and RO is total sum of divalent metal oxides.

According to a sixty-fifth aspect, the glass of any one of aspects58-64, wherein the composition of the components comprises greater thanor equal to 0.0 mol. % and less than or equal to 4.5 mol. % SiO₂.

According to a sixty-sixth aspect, the glass of any one of aspects58-65, wherein the composition of the components comprises greater thanor equal to 10.0 mol. % and less than or equal to 40.0 mol. % B₂O₃,greater than or equal to 10.0 mol. % and less than or equal to 25.0 mol.% La₂O₃, greater than or equal to 1.0 mol. % and less than or equal to30.0 mol. % WO₃, greater than or equal to 0.3 mol. % and less than orequal to 30.0 mol. % TiO₂, greater than or equal to 0.3 mol. % and lessthan or equal to 20.0 mol. % Nb₂O₅, greater than or equal to 0.3 mol. %and less than or equal to 10.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 4.8 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 10.0 mol. % Bi₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 10.0 mol. % Y₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 7.5 mol. %CaO, greater than or equal to 0.0 mol. % and less than or equal to 5.0mol. % BaO, greater than or equal to 0.0 mol. % and less than or equalto 4.0 mol. % Li₂O, greater than or equal to 0.0 mol. % and less than orequal to 4.0 mol. % SrO, greater than or equal to 0.0 mol. % and lessthan or equal to 3.0 mol. % Na₂O and greater than or equal to 0.0 mol. %and less than or equal to 2.0 mol. % K₂O.

According to a sixty-seventh aspect, the glass of any one of aspects58-66, wherein the composition of the components comprises greater thanor equal to 21.5 mol. % and less than or equal to 34.5 mol. % B₂O₃,greater than or equal to 13.0 mol. % and less than or equal to 24.0 mol.% La₂O₃, greater than or equal to 6.0 mol. % and less than or equal to22.0 mol. % TiO₂, greater than or equal to 4.5 mol. % and less than orequal to 18.0 mol. % Nb₂O₅, greater than or equal to 2.0 mol. % and lessthan or equal to 26.0 mol. % WO₃, greater than or equal to 0.5 mol. %and less than or equal to 8.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 4.8 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.5 mol. % Bi₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 6.5 mol. % Y₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 5.5 mol. %CaO, greater than or equal to 0.0 mol. % and less than or equal to 4.6mol. % BaO, greater than or equal to 0.0 mol. % and less than or equalto 3.6 mol. % Li₂O, greater than or equal to 0.0 mol. % and less than orequal to 3.6 mol. % SrO, greater than or equal to 0.0 mol. % and lessthan or equal to 2.7 mol. % Na₂O and greater than or equal to 0.0 mol. %and less than or equal to 1.8 mol. % K₂O.

According to a sixtieth-eighth aspect, the glass of any one of aspects58-67, wherein the composition of the components comprises greater thanor equal to 23.0 mol. % and less than or equal to 33.0 mol. % B₂O₃,greater than or equal to 14.5 mol. % and less than or equal to 22.5 mol.% La₂O₃, greater than or equal to 8.0 mol. % and less than or equal to20.0 mol. % TiO₂, greater than or equal to 6.0 mol. % and less than orequal to 16.5 mol. % Nb₂O₅, greater than or equal to 5.0 mol. % and lessthan or equal to 23.0 mol. % WO₃, greater than or equal to 1.75 mol. %and less than or equal to 7.25 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 4.8 mol. % SiO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.0 mol. % Bi₂O₃, greater thanor equal to 0 mol. % and less than or equal to 5.75 mol. % Y₂O₃, greaterthan or equal to 0 mol. % and less than or equal to 4.75 mol. % CaO,greater than or equal to 0.0 mol. % and less than or equal to 4.0 mol. %BaO, greater than or equal to 0.0 mol. % and less than or equal to 3.2mol. % Li₂O, greater than or equal to 0.0 mol. % and less than or equalto 3.2 mol. % SrO, greater than or equal to 0.0 mol. % and less than orequal to 2.4 mol. % Na₂O and greater than or equal to 0.0 mol. % andless than or equal to 1.6 mol. % K₂O.

According to a sixty-ninth aspect, the glass of any one of aspects58-68, wherein the composition of the components is substantially freeof ZnO.

According to a seventieth aspect, the glass of any one of aspects 58-69,wherein the composition of the components comprises greater than orequal to 0.0 mol. % and less than or equal to 2.0 mol. % Ta₂O₅, greaterthan or equal to 0.0 mol. % and less than or equal to 2.0 mol. % TeO₂,greater than or equal to 0.0 mol. % and less than or equal to 0.5 mol. %GeO₂, greater than or equal to 0.0 mol. % and less than or equal to 0.5mol. % PbO, greater than or equal to 0.0 mol. % and less than or equalto 0.2 mol. % As₂O₃ and greater than or equal to 0.0 mol. % and lessthan or equal to 0.2 mol. % Sb₂O₃, and wherein the composition of thecomponents is substantially free of fluorine and substantially free ofV₂O₅.

According to a seventy-first aspect, the glass of any one of aspects58-70, wherein the glass satisfies the condition: T_(i)≥0.52, whereT_(i) is a transmittance index, calculated from the glass composition interms of mol. % of the components according to the Formula (I):

T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅)  (I).

According to a seventy-second aspect, the glass of the seventy-firstaspect, wherein T_(i)≥0.57.

According to a seventy-third aspect, the glass of the seventy-secondaspect, wherein 0.62≤T_(i)≤0.95.

According to a seventy-fourth aspect, the glass of any one of aspects58-73, wherein the glass satisfies the conditions: 4.5≤P_(d)≤5.5 and1.95≤P_(n)≤2.07.

According to a seventy-fifth aspect, the glass of any one of aspects58-74, wherein the glass has a density at room temperature, d_(RT), thatis greater than or equal to 4.5 and less than or equal to 5.5 and arefractive index at 587.56 nm, n_(d), that is greater than or equal to1.95 and less than or equal to 2.07.

According to a seventy-sixth aspect, the glass of any one of aspects58-75, wherein the glass has a liquidus temperature, T_(liq), that isless than or equal to 1100° C.

According to a seventy-seventh aspect, the glass of the seventy-sixthaspect, wherein the liquidus temperature, T_(liq), is less than or equalto 1050° C.

According to a seventy-eighth aspect, the glass of any one of aspects58-77, wherein the glass further has a decimal logarithm of liquidusviscosity, Log(η_(liq) [P]), that is greater than or equal to 0.50.

According to a seventy-ninth aspect, the glass of the seventy-eighthaspect, wherein the decimal logarithm of liquidus viscosity, Log(η_(liq)[P]), is greater than or equal to 0.75.

According to an eightieth aspect, a glass of any one of aspects 58-79,wherein when cooled in air from 1100° C. to 500° C. in 2.5 minutes, theglass does not crystallize.

According to an eighty-first aspect, a glass of any one of aspects58-80, wherein when having a thickness of 10 mm, the glass can bebleached in less than or equal to 96 hours at a temperature less than orequal to 700° C.

According to an eighty-second aspect, a method for manufacturing anoptical element, the method comprising processing the glass of any oneof aspects 58-81.

According to an eighty-third aspect, an optical element comprising theglass of any one of aspects 58-82.

According to an eighty-fourth aspect, a glass of any one of aspects1-29, wherein the glass has a total transmittance measured on a sampleof 10 mm thickness that is greater than or equal to 70% at a wavelengthof 450 nm.

According to an eighty-fifth aspect, a glass of any one of aspects30-57, wherein the glass has a total transmittance measured on a sampleof 10 mm thickness that is greater than or equal to 70% at a wavelengthof 450 nm.

According to an eighty-sixth aspect, a glass of any one of aspects58-79, wherein the glass has a total transmittance measured on a sampleof 10 mm thickness that is greater than or equal to 70% at a wavelengthof 450 nm.

Many variations and modifications may be made to the above-describedembodiments of the disclosure without departing substantially from thespirit and various principles of the disclosure. All such modificationsand variations are intended to be included herein within the scope ofthis disclosure and protected by the following claims.

To the extent not already described, the different features of thevarious aspects of the present disclosure may be used in combinationwith each other as desired. That a particular feature is not explicitlyillustrated or described with respect to each aspect of the presentdisclosure is not meant to be construed that it cannot be, but it isdone for the sake of brevity and conciseness of the description. Thus,the various features of the different aspects may be mixed and matchedas desired to form new aspects, whether or not the new aspects areexpressly disclosed.

1. A glass comprising a plurality of components, the glass having acomposition of the components comprising: greater than or equal to 3.0mol. % and less than or equal to 35.0 mol. % WO₃, greater than or equalto 0.3 mol. % and less than or equal to 50.0 mol. % TiO₂, greater thanor equal to 0.3 mol. % and less than or equal to 50.0 mol. % Nb₂O₅,greater than or equal to 0.0 mol. % and less than or equal to 20.0 mol.% Bi₂O₃, greater than or equal to 0.0 mol. % and less than or equal to10.0 mol. % TeO₂, greater than or equal to 0.0 mol. % and less than orequal to 5.0 mol. % PbO, greater than or equal to 0.0 mol. % and lessthan or equal to 3.0 mol. % MoO₃, greater than or equal to 0.0 mol. %and less than or equal to 1.0 mol. % V₂O₅, greater than or equal to 0.0at. % and less than or equal to 5.0 at. % F, greater than or equal to0.0 at. % and less than or equal to 1.0 at. % Cl, greater than or equalto 0.0 at. % and less than or equal to 1.0 at. % Br, greater than orequal to 0.0 at. % and less than or equal to 1.0 at. % I, greater thanor equal to 0.6 mol. % and less than or equal to 60.0 mol. % TiO₂+Nb₂O₅and optionally comprising one or more components selected from Al₂O₃,B₂O₃, BaO, CaO, Gd₂O₃, GeO₂, K₂O, La₂O₃, Li₂O, MgO, Na₂O, P₂O₅, SiO₂,SrO, Ta₂O₅, Y₂O₃, Yb₂O₃, ZnO and ZrO₂, wherein the glass has a liquidustemperature, T_(liq), that is greater than or equal to 850° C. and lessthan or equal to 1350° C., and wherein the glass satisfies theconditions:1.92≤P _(n)≤2.08 and P _(n)−(1.437+0.0005*T _(liq))>0.00, where P_(n) isa refractive index parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (II):P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)where a symbol “*” means multiplication.
 2. The glass of claim 1,wherein the glass has a refractive index at 587.56 nm, n_(d), that isgreater than or equal to 1.92 and less than or equal to 2.08 and whereinthe glass satisfies the condition:n _(d)−(1.437+0.0005*T _(liq))>0.00.
 3. The glass of claim 1, whereinthe composition of the components comprises: greater than or equal to0.3 mol. % and less than or equal to 20.0 mol. % ZrO₂, greater than orequal to 0.0 mol. % and less than or equal to 25.0 mol. % ZnO, greaterthan or equal to 0.0 mol. % and less than or equal to 10.0 mol. % P₂O₅,greater than or equal to 0.0 mol. % and less than or equal to 5.0 mol. %GeO₂, greater than or equal to 17.0 mol. % TiO₂+Nb₂O₅+ZrO₂ and whereinthe composition of the components satisfies the condition:0≤B₂O₃+SiO₂−P₂O₅[mol. %]≤40.
 4. The glass of claim 1, wherein thecomposition of the components comprises: greater than or equal to 10.0mol. % and less than or equal to 40.0 mol. % B₂O₃, greater than or equalto 10.0 mol. % and less than or equal to 25.0 mol. % La₂O₃, greater thanor equal to 3.0 mol. % and less than or equal to 30.0 mol. % WO₃,greater than or equal to 0.3 mol. % and less than or equal to 30.0 mol.% TiO₂, greater than or equal to 0.3 mol. % and less than or equal to20.0 mol. % Nb₂O₅, greater than or equal to 0.0 mol. % and less than orequal to 15.0 mol. % SiO₂, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % Bi₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % Y₂O₃, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % ZrO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.5 mol. % CaO, greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % BaO, greaterthan or equal to 0.0 mol. % and less than or equal to 4.0 mol. % Li₂O,greater than or equal to 0.0 mol. % and less than or equal to 4.0 mol. %SrO, greater than or equal to 0.0 mol. % and less than or equal to 3.0mol. % Na₂O and greater than or equal to 0.0 mol. % and less than orequal to 2.0 mol. % K₂O.
 5. The glass of claim 1, wherein thecomposition of the components comprises: greater than or equal to 23.0mol. % and less than or equal to 33.0 mol. % B₂O₃, greater than or equalto 14.5 mol. % and less than or equal to 22.5 mol. % La₂O₃, greater thanor equal to 8.0 mol. % and less than or equal to 20.0 mol. % TiO₂,greater than or equal to 6.0 mol. % and less than or equal to 16.5 mol.% Nb₂O₅, greater than or equal to 5.0 mol. % and less than or equal to23.0 mol. % WO₃, greater than or equal to 1.75 mol. % and less than orequal to 7.25 mol. % ZrO₂, greater than or equal to 0.0 mol. % and lessthan or equal to 11.5 mol. % SiO₂, greater than or equal to 0.0 mol. %and less than or equal to 7.0 mol. % Bi₂O₃, greater than or equal to 0mol. % and less than or equal to 5.75 mol. % Y₂O₃, greater than or equalto 0 mol. % and less than or equal to 4.75 mol. % CaO, greater than orequal to 0.0 mol. % and less than or equal to 4.0 mol. % BaO, greaterthan or equal to 0.0 mol. % and less than or equal to 3.2 mol. % Li₂O,greater than or equal to 0.0 mol. % and less than or equal to 3.2 mol. %SrO, greater than or equal to 0.0 mol. % and less than or equal to 2.4mol. % Na₂O and greater than or equal to 0.0 mol. % and less than orequal to 1.6 mol. % K₂O.
 6. The glass of claim 1, wherein thecomposition of the components comprises: greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. % Y₂O₃, greater than or equalto 0.0 mol. % and less than or equal to 2.0 mol. % Ta₂O₅, greater thanor equal to 0.0 mol. % and less than or equal to 2.0 mol. % TeO₂,greater than or equal to 0.0 mol. % and less than or equal to 0.5 mol. %GeO₂, greater than or equal to 0.0 mol. % and less than or equal to 0.5mol. % PbO, greater than or equal to 0.0 mol. % and less than or equalto 0.2 mol. % As₂O₃ and greater than or equal to 0.0 mol. % and lessthan or equal to 0.2 mol. % Sb₂O₃, and wherein the composition of thecomponents is substantially free of fluorine and substantially free ofV₂O₅.
 7. The glass of claim 1, wherein the glass satisfies theconditions:4.5≤P _(d)≤5.5 and1.95≤P _(n)≤2.07, where P_(n) is a refractive index parameter,calculated from the glass composition in terms of mol. % of thecomponents according to the Formula (II):P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)P_(d) is a density parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (III):P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)wherein a symbol “*” means multiplication.
 8. The glass of claim 1,wherein when cooled in air from 1100° C. to 500° C. in 2.5 minutes, theglass does not crystallize.
 9. A glass comprising a plurality ofcomponents, the glass having a composition of the components comprising:greater than or equal to 7.5 mol. % and less than or equal to 28.0 mol.% TiO₂, greater than or equal to 1.0 mol. % and less than or equal to40.0 mol. % B₂O₃, greater than or equal to 0.3 mol. % and less than orequal to 19.5 mol. % Nb₂O₅, greater than or equal to 0.0 mol. % and lessthan or equal to 35.0 mol. % WO₃, greater than or equal to 0.0 mol. %and less than or equal to 25.0 mol. % La₂O₃, greater than or equal to0.0 mol. % and less than or equal to 25.0 mol. % Gd₂O₃, greater than orequal to 0.0 mol. % and less than or equal to 20.0 mol. % Bi₂O₃, greaterthan or equal to 0.0 mol. % and less than or equal to 20.0 mol. % ZrO₂,greater than or equal to 0.0 mol. % and less than or equal to 20.0 mol.% TeO₂, greater than or equal to 0.0 mol. % and less than or equal to13.5 mol. % SiO₂, greater than or equal to 0.0 mol. % and less than orequal to 10.0 mol. % Al₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % ThO₂, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % GeO₂, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % Ta₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % PbO, greaterthan or equal to 0.0 mol. % and less than or equal to 1.0 mol. % V₂O₅,greater than or equal to 0.0 at. % and less than or equal to 5.0 at. %F, greater than or equal to 0.0 at. % and less than or equal to 1.0 at.% Cl, greater than or equal to 0.0 at. % and less than or equal to 1.0at. % Br, greater than or equal to 0.0 at. % and less than or equal to1.0 at. % I, greater than or equal to 10.0 mol. %RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, less than or equal to 40.0 mol. % WO₃+TiO₂,less than or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than or equal to0.0 mol. % and less than or equal to 5.0 mol. % R₂O+RO and optionallycomprising P₂O₅, wherein the composition of the components satisfies theconditions:TiO₂−SiO₂[mol. %]≥7.5 andB₂O₃+SiO₂−P₂O₅[mol. %]≥0.00, and wherein the glass satisfies theconditions:1.9≤P _(n)≤2.1 andP _(ref)−(0.269−0.12*T _(i))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)P_(ref) is a refraction parameter, calculated from the glass compositionin terms of mol. % of the components according to the Formula (IV):P_(ref)(cm³/g)=0.000087034*SiO₂−0.00012035*B₂O₃−0.0012566*La₂O₃+0.0011411*TiO₂−0.00031654*ZnO+0.000088066*CaO+0.0020444*Nb₂O₅−0.00023383*MgO−0.00086501*BaO−0.0004486*WO₃−0.0014114*Gd₂O₃−0.00023872*Y₂O₃−0.00031575*Ta₂O₅+0.00011894*Li₂O+0.00027178*Al₂O₃−0.000099802*Na₂O−0.00028391*GeO₂−0.00030531*SrO−0.00072061*Bi₂O₃−0.0010964*Yb₂O₃+0.00022839*K₂O−0.00086617*PbO+0.00027129*TeO₂+0.198,  (IV)where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, R₂O is a total sum of monovalent metal oxides, RO is a totalsum of divalent metal oxides, and an asterisk (*) means multiplication.10. The glass of claim 9, wherein the glass has a refractive index at587.56 nm, n_(d), that is greater than or equal to 1.9 and less than orequal to 2.1 and wherein the glass satisfies the condition:(n _(d)−1)/d _(RT)−(0.269−0.12*T _(i))>0.00, where d_(RT) (g/Cm³) is adensity at room temperature, T_(i) is a transmittance index, calculatedfrom the glass composition in terms of mol. % of the componentsaccording to the formula:T _(i)=(La₂O₃+Gd₂O₃+ZrO₂+WO₃)/(La₂O₃+Gd₂O₃+ZrO₂+WO₃+TiO₂+Nb₂O₅).
 11. Theglass of claim 9, wherein the composition of the components comprises:greater than or equal to 10.0 mol. % and less than or equal to 40.0 mol.% B₂O₃, greater than or equal to 10.0 mol. % and less than or equal to25.0 mol. % La₂O₃, greater than or equal to 0.0 mol. % and less than orequal to 30.0 mol. % WO₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % Bi₂O₃, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % Y₂O₃, greater than or equal to 0.0mol. % and less than or equal to 10.0 mol. % ZrO₂, greater than or equalto 0.0 mol. % and less than or equal to 7.5 mol. % CaO, greater than orequal to 0.0 mol. % and less than or equal to 5.0 mol. % BaO, greaterthan or equal to 0.0 mol. % and less than or equal to 4.0 mol. % Li₂O,greater than or equal to 0.0 mol. % and less than or equal to 4.0 mol. %SrO, greater than or equal to 0.0 mol. % and less than or equal to 3.0mol. % Na₂O and greater than or equal to 0.0 mol. % and less than orequal to 2.0 mol. % K₂O.
 12. The glass of claim 9, wherein thecomposition of the components comprises: greater than or equal to 23.0mol. % and less than or equal to 33.0 mol. % B₂O₃, greater than or equalto 14.5 mol. % and less than or equal to 22.5 mol. % La₂O₃, greater thanor equal to 8.0 mol. % and less than or equal to 20.0 mol. % TiO₂,greater than or equal to 6.0 mol. % and less than or equal to 16.5 mol.% Nb₂O₅, greater than or equal to 5.0 mol. % and less than or equal to23.0 mol. % WO₃, greater than or equal to 1.75 mol. % and less than orequal to 7.25 mol. % ZrO₂, greater than or equal to 0.0 mol. % and lessthan or equal to 11.5 mol. % SiO₂, greater than or equal to 0.0 mol. %and less than or equal to 7.0 mol. % Bi₂O₃, greater than or equal to 0mol. % and less than or equal to 5.75 mol. % Y₂O₃, greater than or equalto 0 mol. % and less than or equal to 4.75 mol. % CaO, greater than orequal to 0.0 mol. % and less than or equal to 4.0 mol. % BaO, greaterthan or equal to 0.0 mol. % and less than or equal to 3.2 mol. % Li₂O,greater than or equal to 0.0 mol. % and less than or equal to 3.2 mol. %SrO, greater than or equal to 0.0 mol. % and less than or equal to 2.4mol. % Na₂O and greater than or equal to 0.0 mol. % and less than orequal to 1.6 mol. % K₂O.
 13. The glass of claim 9, wherein thecomposition of the components comprises: greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. % Y₂O₃, greater than or equalto 0.0 mol. % and less than or equal to 2.0 mol. % Ta₂O₅, greater thanor equal to 0.0 mol. % and less than or equal to 2.0 mol. % TeO₂,greater than or equal to 0.0 mol. % and less than or equal to 0.5 mol. %GeO₂, greater than or equal to 0.0 mol. % and less than or equal to 0.5mol. % PbO, greater than or equal to 0.0 mol. % and less than or equalto 0.2 mol. % As₂O₃ and greater than or equal to 0.0 mol. % and lessthan or equal to 0.2 mol. % Sb₂O₃, and wherein the composition of thecomponents is substantially free of fluorine and substantially free ofV₂O₅.
 14. The glass of claim 9, wherein the glass satisfies theconditions:4.5≤P _(d)≤5.5 and1.95≤P _(n)≤2.07, where P_(d) is a density parameter, calculated fromthe glass composition in terms of mol. % of the components according tothe Formula (III):P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂.  (III)15. The glass of claim 9, wherein when cooled in air from 1100° C. to500° C. in 2.5 minutes, the glass does not crystallize
 16. A glasscomprising a plurality of components, the glass having a composition ofthe components comprising: greater than or equal to 1.0 mol. % and lessthan or equal to 40.0 mol. % WO₃, greater than or equal to 0.3 mol. %and less than or equal to 20.0 mol. % ZrO₂, greater than or equal to 0.0mol. % and less than or equal to 40.0 mol. % B₂O₃, greater than or equalto 0.0 mol. % and less than or equal to 35.0 mol. % La₂O₃, greater thanor equal to 0.0 mol. % and less than or equal to 35.0 mol. % Bi₂O₃,greater than or equal to 0.0 mol. % and less than or equal to 35.0 mol.% ZnO, greater than or equal to 0.0 mol. % and less than or equal to25.0 mol. % Ta₂O₅, greater than or equal to 0.0 mol. % and less than orequal to 10.0 mol. % Al₂O₃, greater than or equal to 0.0 mol. % and lessthan or equal to 10.0 mol. % ThO₂, greater than or equal to 0.0 mol. %and less than or equal to 10.0 mol. % TeO₂, greater than or equal to 0.0mol. % and less than or equal to 5.0 mol. % V₂O₅, greater than or equalto 10.0 mol. % RE₂O₃+ZrO₂+TiO₂+Nb₂O₅+WO₃, greater than or equal to 0.0mol. % and less than or equal to 35.0 mol. % TiO₂+Nb₂O₅, greater than orequal to 0.0 mol. % and less than or equal to 4.8 mol. % SiO₂+GeO₂ andoptionally comprising one or more components selected from P₂O₅, BaO,CaO, K₂O, Li₂O, MgO, Na₂O, PbO and SrO, wherein the composition of thecomponents satisfies the condition:B₂O₃+SiO₂−P₂O₅[mol. %]≥0.50, and wherein the glass satisfies theconditions:500° C.≤P _(Tg)≤700° C.,P _(d)<6.0 g/cm³ andP _(n)−(1.571+0.083*P _(d))>0.00, where P_(n) is a refractive indexparameter, calculated from the glass composition in terms of mol. % ofthe components according to the Formula (II):P_(n)=−0.0051086*Al₂O₃−0.0049247*B₂O₃−0.00034289*BaO+0.0086552*Bi₂O₃−0.0014511*CaO+0.0047429*Gd₂O₃−0.0033126*GeO₂−0.0049544*K₂O+0.0045475*La₂O₃−0.0023329*Li₂O−0.0026561*MgO−0.0035925*Na₂O+0.0071165*Nb₂O₅−0.0075074*P₂O₅+0.0015814*PbO−0.0043959*SiO₂−0.00086373*SrO+0.0045915*Ta₂O₅−0.0015272*TeO₂+0.0020281*TiO₂+0.0012709*WO₃+0.0025878*Y₂O₃+0.0048156*Yb₂O₃−0.00047962*ZnO+0.00090073*ZrO₂+1.955,  (II)P_(d) is a density parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (III):P_(d)(g/cm³)=4.95−0.036300*Al₂O₃−0.028364*B₂O₃+0.010786*BaO+0.077280*Bi₂O₃−0.0047086*CaO+0.060989*Er₂O₃+0.067356*Gd₂O₃−0.024973*K₂O+0.050388*La₂O₃−0.015411*Li₂O−0.014318*Na₂O−0.0016283*Nb₂O₅+0.078354*Nd₂O₃−0.045034*P₂O₅+0.037463*PbO−0.026153*SiO₂−0.0079191*TeO₂−0.015844*TiO₂+0.020220*WO₃+0.016362*Y₂O₃+0.058765*Yb₂O₃+0.0086588*ZnO+0.0043754*ZrO₂,  (III)P_(Tg) is a T_(g) parameter, calculated from the glass composition interms of mol. % of the components according to the Formula (V):P _(Tg)(°C.)=595.358−0.63217*B₂O₃−0.46552*SiO₂+1.1849*TiO₂+0.59610*Nb₂O₅−1.6293*WO₃+1.3877*ZrO₂+4.4090*La₂O₃+4.1695*Y₂O₃−5.0756*Bi₂O₃+0.55630*CaO−5.3892*PbO−4.2774*TeO₂+1.8497*Al₂O₃−0.40659*GeO₂−1.7011*ZnO−4.1520*Li₂O+3.0777*Gd₂O₃,  (V)where RE₂O₃ is a total sum of rare earth metal oxides in trivalentequivalent, and an asterisk (*) means multiplication.
 17. The glass ofclaim 16, wherein the glass has a glass transition temperature, T_(g),that is greater than or equal to 500° C. and less than or equal to 700°C. and a density at room temperature, d_(RT), that is less than or equalto 6.0 g/cm³ and wherein the glass satisfies the condition:n _(d)−(1.571+0.083*d _(RT))>0.00, where n_(d) is a refractive index at587.56 nm.
 18. The glass of claim 16, wherein the composition of thecomponents comprises: greater than or equal to 23.0 mol. % and less thanor equal to 33.0 mol. % B₂O₃, greater than or equal to 14.5 mol. % andless than or equal to 22.5 mol. % La₂O₃, greater than or equal to 8.0mol. % and less than or equal to 20.0 mol. % TiO₂, greater than or equalto 6.0 mol. % and less than or equal to 16.5 mol. % Nb₂O₅, greater thanor equal to 5.0 mol. % and less than or equal to 23.0 mol. % WO₃,greater than or equal to 1.75 mol. % and less than or equal to 7.25 mol.% ZrO₂, greater than or equal to 0.0 mol. % and less than or equal to4.8 mol. % SiO₂, greater than or equal to 0.0 mol. % and less than orequal to 7.0 mol. % Bi₂O₃, greater than or equal to 0 mol. % and lessthan or equal to 5.75 mol. % Y₂O₃, greater than or equal to 0 mol. % andless than or equal to 4.75 mol. % CaO, greater than or equal to 0.0 mol.% and less than or equal to 4.0 mol. % BaO, greater than or equal to 0.0mol. % and less than or equal to 3.2 mol. % Li₂O, greater than or equalto 0.0 mol. % and less than or equal to 3.2 mol. % SrO, greater than orequal to 0.0 mol. % and less than or equal to 2.4 mol. % Na₂O andgreater than or equal to 0.0 mol. % and less than or equal to 1.6 mol. %K₂O.
 19. The glass of claim 16, wherein the composition of thecomponents comprises: greater than or equal to 0.0 mol. % and less thanor equal to 2.0 mol. % Ta₂O₅, greater than or equal to 0.0 mol. % andless than or equal to 2.0 mol. % TeO₂, greater than or equal to 0.0 mol.% and less than or equal to 0.5 mol. % GeO₂, greater than or equal to0.0 mol. % and less than or equal to 0.5 mol. % PbO, greater than orequal to 0.0 mol. % and less than or equal to 0.2 mol. % As₂O₃ andgreater than or equal to 0.0 mol. % and less than or equal to 0.2 mol. %Sb₂O₃, and wherein the composition of the components is substantiallyfree of fluorine and substantially free of V₂O₅.
 20. The glass of claim16, wherein when cooled in air from 1100° C. to 500° C. in 2.5 minutes,the glass does not crystallize.